Reframing past events to serve a current plot need. The ideal retcon clarifies a question alluded to without adding excessive new questions. In its most basic form, this is any plot point that was not intended from the beginning. The most preferred use is where it contradicts nothing, even though it was changed later on.
While the term comes from comic books, dating to All-Star Squadron #18 in 1983 and shortened to "retcon" by the end of the decade, the technique is much older. Often, it's used to serve a new plot by changing its context; however, it's also done when the creators are caught writing a story that violates continuity and isn't very plausible.
In Marvel Comics, the person who pointed out the problem and at the same time provided a plausible explanation was awarded a Genuine Marvel Comics No-Prize by editor Stan Lee, a tradition that was kept alive by other editors after he became publisher.
See also Ass Pull, which is something that was not properly set up before it is sprung on the audience. It is related to Deus ex Machina. Some but not all retcons are Ass Pulls, and a good retcon can actually improve the current narrative. A good way to get away with a retcon is to reveal new implications or motivations for events that have already been established.
Smoother retcons won't be distinguishable as such, and can even make what was initially an Ass Pull later look like everything was Just as Planned. (In other words, No Prize it into plausibility and away from the dizzying realm of the Ass Pull.)
The retcon is considered by many to occur when current events contradict the past continuity of the series and is evidence of a Writer on Board. Perhaps more often, the retcon does not actually violate canon, but rather violates fanon, the set of unstated interpretations usually made by the audience (an interpretation violated this way is said to be Jossed). Most competent writers achieve a retcon by relying on a less-obvious but still perfectly valid interpretation of what was previously seen.
As the number of twists and misdirections in a story becomes higher, it becomes more difficult to tell whether an event actually is a retcon (which implies that the writers changed their minds), or a misdirection (which implies that the writers intended the "retconned" version all along, and had been deliberately misleading the audience before). In some cases, it is impossible to tell, short of reading the author's mind (even then, it might not helped, as it's entirely possible for an author to be on the fence about what they're planning to do).
A retcon may be used as part of an Armed with Canon campaign launched by one author against the work of another author in the same Shared Universe. Over-use of retcons can result in Continuity Snarl. It can also result in your readers and fans approaching the work with a certain degree of skepticism, cynicism or even complete uninterest, especially if you tend to obviously and quickly retcon away that which turns out to be unpopular or drastically challenges or changes the status quo — after all, why get involved in your latest Crisis Crossover Event which promises to Change Everything Forever and that Nothing Will Be The Same Again if there's a good chance it'll all just be retconned away after a short period of time?
This happens very easily with prequels when the writers aren't being very careful. On the other hand, Tropes Are Not Bad. It's entirely possible that an author will retcon his own work to fix a Continuity Snarl or even apply an Author's Saving Throw if things get really hairy.
Compare Flip Flop of God. Tends to come in The Reveal format. May involve Opening a Can of Clones. Can at times also qualify as a Throw It In.
In the last page of chapter 238, Makie shows up with her friends in kid form, looking smaller than Negi. In the first page of the next chapter, in the very same scene, she is now in teenage form and Marshmallows Negi.
The posted "birth date" of the title character changed from the fairly vague "Summer 1993" to the even more vague "1994" between the magazine version of Chapter 10 and the publication of Volume 2. This works as a Revision, as it renders Negi's in-story usage of a historical Japanese method of age reckoning correct, but also makes determining his actual age more difficult.
Somewhere between volume 5 and 11 of the English-language Great Teacher Onizuka manga, the average age of the protagonist's class gets bumped from 14 to 16.
The Gundam canon has a pretty significant number of these.
The Biosensor from Zeta Gundam. Said to be a device that somehow increases a mobile suit's power based on the pilot's Newtype abilities, the original series events that are attributed to this system are actually far more supernatural in nature. The Zeta Gundam and ZZ Gundam both have the apparent ability to channel the souls of the dead, as well as the pilot's own fury, to increase the power of the unit. The Biosystem explanation may have been added to keep the show closer to a Real Robot style of show, while still allowing these scenes to be unaffected.
Tomino then went on to write the CG short Gundam Evolve 5, which depicts a battle from Mobile Suit Gundam: Char's Counterattack with a more positive outcome; Tomino has said he considers the short to be the "New Translation" version of CCA.
One of the most infamous Ret Cons was the end of the Gundam SEED Special Edition. A scene specifically put in to reinforce a main character's death was edited out to enable an exceedingly unlikely comeback.
The HD Remaster versions of Gundam SEED went further with its retcons, changing a second death from "self-defense" to "an accident in the most Narmiest way possible" and introduced a brand new weapon that wasn't used in either the original nor the Special Editions. The HD Remaster for Mobile Suit Gundam SEED Destiny sets to do the same thing.
One episode of Digimon Adventure 02 has a flashback of the season one characters giving up their ability to evolve past a certain level (and by extension, their ability to be of any use in a fight). This comes up right in the middle of the season, soon after the Applied Phlebotinum the now-reformed Ken was using to obstruct their evolution is destroyed, and basically comes across as a cheap excuse to keep the old characters out of the Competence Zone. It also gave Patamon and Gatomon (two heroes from 01 that made the main cast in 02) a reason to DNA digivolve.
Hayate the Combat Butler: For those who haven't read the manga, this seems to happen between the first and second seasons of the anime. In the last episode of the first season Ayumu and Hinagiku are shown to know each other (well enough for them to travel to the Parthenon together), but in the second season, they acted as if they'd never met. In the same episode, it's stated that Hayate's been Nagi's butler for over a year, whereas in the first episode of season 2, Klaus says Hayate's only been Nagi's butler for a month.
However, this is easily explained by the fact that the events of the last episode of the first season of the anime (Ayumu and Hina's parthenon trip and Hayate and Nagi's trip to the Aegean sea) were, in the original manga, side-stories that took place during the golden week holidays and that were out of sync with the rest of the series' continuity.
Some chapters of Bleach contradict Big Bad Aizen Sousuke's description of past events:
Aizen says that Kisuke Urahara was exiled for creating a gigai that was untracable, and destroyed the reiatsu of the shinigami using it, both things Urahara actually did. In the "Turn Back the Pendulum" chapters, on the other hand, Urahara's exile is the result of Aizen framing him for turning Hirako and the others into Hollows, something Aizen actually did (Urahara then used the infamous gigai to ensure all the exiles could escape punishment). Fandom speculation over why Aizen lied ranged from observing the Bleachverse does have official public knowledge and privately known true knowledge to Aizen sowing a seed of discord between Ichigo and Urahara by attempting to make Ichigo mistrust Urahara. Aizen himself does eventually point out that he has his own personal definition of "reality" which means he lies on a regular basis, and takes pleasure in doing so. He tells Ichigo it's idiotic to trust anything he says.
Some initial character designs are retconned beyond the bounds of the series' Art Evolution in later appearances, such as the location of Ulquiorra's hollow hole.
In the third Megami sound stage, Hayate says that Fate is more of a sister to Vivio, and Nanoha says that while Fate loves Vivio, she is keeping some distance from her. In ViVid, Vivio says she still considers both of them her mothers, and Fate once refers to herself in the third person as "Fate-mama" while talking to Vivio.
Also from the Vivid manga, it's stated that Vivio lost the Saint's Armor ability due to being hit by Nanoha's Starlight Breaker, which contradicts a scene from the Striker(s) manga, in which she was stated to be fine after a medical checkup.
In earlier manga chapters , Gaara had triple-pierced ears despite his automatic sand shield, which (almost always) prevents him from taking physical damage.
The existence of the nine Tailed Beasts. During the chunin exam arc, Shukaku was stated to have been a wind spirit and the soul of a mad priest, as well as not even being hinted as having any relation to the Nine-Tails.
Even the relationship between Naruto and the Kyūbi is a retcon; the very first chapter has an older, experienced ninja telling Naruto that he is the sealed Kyūbi rather than containing it and that that's why everyone hates him. Given the extreme emphasis later chapters place on the tailed beasts and the cultural tradition of using people to contain them, it's unthinkable that an experienced ninja could make that mistake, or that everyone else would just let it go unchallenged.
The Space Battleship Yamato movie was meant to end the story, so the ending has many core crew members, including Kodai and Yuki, dead with the Yamato destroyed in a suicide charge. After fan outcry, the movie was adapted into the second season TV series with a different ending so that the ship is not destroyed and most crew members live. Several movies and a third TV season later, the second movie is just claimed never to have happened.
In Eyeshield 21, Agon's hair is a walking retcon. In one flashback to his 10th grade year he had short blonde hair and in another he had incredibly long dreads. In middle school, depending on whose reminiscing, Agon either had short thick dreads, long thick dreads, short thin dreads, or shoulder-length blonde hair.
Nirvana, a giant walking weapon, was initially drawns with 8 legs but suddenly had 6 when the method by which it had to be destroyed was determined. The characters explain this via Shrug of God in the Q&A section afterward.
Lisanna, Natsu's deceased childhood friend, was revealed to have been transported to the Mirror World of Edolas, instead of having died. Earlier chapters even showed her burial.
They found the body of the dead Edolas Lissana which fell on Eathland, so the burial still makes sense.
Early on in Soul Eater, Liz Thompson briefly remembers her and Patty's Backstory, saying that her life took a turn for the bizarre on that day that she got high and tried to mug a Shinigami (Kid). A couple dozen chapters later, it's instead revealed that Kid came to New York specifically to recruit the Thompson sisters as his weapons, no mugging involved. They went along for the ride, at least initially, to milk him for all the money and convenience he could provide them, before coming to admire him for real.
The two events could have both happened though, since the later chapter didn't specifically deny the mugging. What could have happened is that he came looking for Liz and Patty, they tried to mug him but Kid got away, and he came back to them at later chance to recruit them.
In the original Japanese version, we see that the five bearers of the Mark of the Dragon are Yusei (tail), Jack (wings), Luna (claw), and Akiza (other claw). This is true for the English version too, with the fifth signer being unknown in both versions. Then, the English version mentioned that Rex Goodwin bears the final mark, before Japan even knew it. Because it was false information. Japan later aired their episode to show that Rowan has the head of the dragon. After this, the English version just pretended that they never said Rex had it.
When the Signers first realize that their marks look like the Crimson Dragon, Yusei incorrectly states (in the English version) that his is the head, not the tail. And it became even more confusing when Rowan and Rex were defeated, with Yusei actually gaining the real head, and transferring his tail mark to Crow. This was barely even addressed in the English version, despite the fact that it's tattooed onto their freaking arms.
Pokémon: In his first appearance, Santa Claus had a Ponyta pulling his sleigh, because the franchise didn't have any deer Pokemon in Gen I. But when Gen II came out and Stantler was introduced, all further Santa appearances had him with a Stantler pulling the sleigh.
The Best Wishes had what was essentially a retcon, though the original eps never aired. Team Plasma was supposed to meet and battle Team Rocket early in the Unova storyline, but the episodes were shelved because of the 2011 earthquake in Japan-part of the storyline involved the destruction of several buildings. Some hoped they might be aired later, but instead,the two teams finally met in the 'Season 2, Episode N' arc, the 'Adventures in Unova' arc in the US. This retconned the plots of the unaired eps out of existence.
At the end of the Mirrodin novels of the Magic: The Gathering world, Glissa activates the Soul Traps and sends all of the inhabitants of the plane back to their original homes, leaving only her, Slobad and Geth's head on Mirrodin to act as wardens for the Mirari. When the plane was revisited years later in the Scars of Mirrodin block, this was retconned so that only those who weren't born on Mirrodin were returned to their original planes, and that the "native" Mirrans had been left behind.
Wizards also confirmed that the Guilds of Ravnica had pretty much dissolved, shortly before Return to Ravnica was announced and it turned out that they were still going strong.
Any time a comic has on its cover the following phrase: "EVERYTHING YOU KNEW ABOUT [X] IS WRONG!", look out, retcon incoming, full force.
So that one of the X-Men wouldn't end up committing Genocide, Jean Grey was rewritten so that she was never Phoenix and she never died on The Moon. It was the Phoenix Force itself, who took on Jean's appearance and memories (Quasi-confirmed in a later issue of What If..? which showed what would have happened if "Jean" had had her powers stripped rather than committing suicide). Has been retconned several times since then, the latest version is that it was Jean on the Moon. How she ended up in Jamaica Bay a few years after that isn't accounted for.
Plus becoming Phoenix in the first place was a retcon. Xavier basically went "Oh, she had this powerful other self in her the whole time, that I just sealed away."
From an X-Menfan-parody film on Magneto's retcon survival: "No, that was actually Xorn's twin brother possessed by the sentient mold Sublime, pretending to be me, pretending to be Xorn." As crazy as that sounds, the parody writer is not making that up.
Beast: That defies all logic!
"Hey guys, there was a secret team of X-Men that I, Professor Xavier, sent off to their deaths. I really didn't mention it before because I thought that it would have been far too depressing for you guys, and because I am the biggest bastard on the planet. Now go on out there and save that world that both hates and fears us!" (X-Men: Deadly Genesis seemed like it was designed for the sole purpose of smearing Professor Xavier's reputation.)
It should be noted the original story clearly stated the reason why Xavier even decided to gather an all-new team of mutants to rescue the first instead of asking for help from their various superhero allies was that the Living Island was telepathically messing with HIS mind so that he would bring it more food (mutants).
Psylocke's Race Lift from a Caucasian British woman to a Japanese assassin was originally explained by Claremont as being the result of magic and surgery performed on her by Spiral and Mojo. After the title changed writers to Fabian Nicieza, he had not been aware of Claremont's explanation and introduced the character Revanche, who was said to be inhabiting Betsy's original body. In his version of events, Spiral and Mojo performed a body-swap on the two women, although he'd later state that their DNA and appearances became intermingled due to imperfections made in the swap. An initial earlier explanation by Nicieza had also stated that Kwannon had accidentally swapped her mind with Betsy after encountering her body on a beach, but this was retconned as false memories due to the inconsistency with what was shown when Betsy originally emerged from the Siege Perilous.
In the late 90's, when Chris Claremont once more began writing for the X-Men, the character Sage was retconned to being one of Xavier's original students, placed as a spy in the Hellfire Club under Sebastian Shaw.
Superman: His origin, early years, and powers have been revamped a ridiculous number of times just in "official" comic book continuity (and not counting in-story changes). Probably the most notable and drastic example took place in John Byrne's "Man of Steel," commissioned by DC in the 1980s to "clean up" the past several decades of Superman continuity by revamping his origin and the story of how he began his superhero career. Among other things, this retcon scaled back Superman's powers from the ridiculous levels they had been inflated to (although they have since begun to creep back up a bit), re-established Superman as the only surviving Kryptonian (that one didn't stick either), and wiped out previous continuity in which Clark Kent had a hero career as a teenager in Smallville using the name Superboy, during which time he also befriended the young Lex Luthor.
That last retcon is also notable for completely borking the continuity of the Legion of Super-Heroes comic, since the eponymous Legion was introduced in the Silver Age as a group of thirtieth-century teenagers who were inspired to form their own "hero club" by stories of Superboy's exploits. The Legion's writers at the time tried to patch things up by, variously, establishing that Superboy had only existed in a pocket universe, killing off the pocket universe Superboy, revamping one-shot character Mon-El into a Superboy Expy, further rejiggering the timeline by having Mon-El kill the Time Trapper, and finally scrapping and rebooting the whole damn thing during the Zero Hour crossover in 1994.
The Legion of Super-Heroes was then rebooted again in 2001, and then retconned again in 2007 back to a variant on the original continuity, with some adjustments. By this point, alternate timelines, retcons, and reboots are a fact of life for Legion fans.
Another major Superman retcon that most people don't know about is his attitude. Siegel and Shuster originally wrote him as very rough and aggressive. On one occasion he kidnapped a slumlord, trapped the man in one of his own shoddy buildings, and threatened to collapse the whole structure on top of the guy if he didn't promise to improve conditions for his tenants. He also "accidentally" snapped the neck of a wife beater. A far cry from the Big Blue Boy Scout we all know and love today. World War II shifted his priorities into patriotism and he became a champion for "Truth, Justice and the American Way". When the Comics Code Authority came into being in the early 50s, it's restrictions on characters' behavior ensured Superman became really square.
Also happens to Superman's cousin, Supergirl. Not only have there been four separate versions, but the pre-New 52's version's history became so convoluted on its own that Sterling Gates just retconned it out in issue 35, to give her the simple story we all thought was true before.
The reason for the massive continuity snarl around Supergirl is because of an editorial mandate that Superman be the only surviving Kryptonian when his own continuity was rewritten and simplified after the Crisis on Infinite Earths. (During the Silver Age, so many other survivors had appeared that it was weakening his story.) This caused obvious problems for Supergirl (which in turn broke the Legion of Super-Heroes, among other things, since it was heavily interconnected with her), and necessitated increasingly convoluted explanations until they finally just threw up their hands, admitted that casual readers would always assume she was Superman's surviving cousin regardless, and switched it back to that.
In another comic-book retcon, Batman is now known as a superhero who refuses to use a gun or to kill (well, most of the time). This was not true in the first year or so, although he didn't actually kill humans very often and most villains died from Karmic Death. See Pay Evil unto Evil.
Batman has enough to fill the list. One of the most notable concerns events in the story arc Hush. The titular villain appears revealed as long dead Robin Jason Todd, before he turns out to be an imposter (and not the real Hush, at that). Later, a ret con revises the story so that it was a resurrected Todd after all, but he escaped to be replaced by the imposter mid-battle.
The Spider-Man stories "One More Day" and "Brand New Day" infamously altered twenty years worth of continuity by erasing Peter Parker and Mary Jane Watson's marriage from continuity. This happened because Spider-Man saved his aunt's life by making a deal with Mephisto, a "demon" character typically used as the Marvel Universe stand-in for the Devil.
Not that before was any picnic. Like with JMS's "Spider-Totem" story, implying that there was fate or something profound lingering over Spider-Man's simple origin story.
Infamously, The Clone Saga had to muck around with continuity so much (both because of its initial premise and because of the unholy mess it later became) that at one point they had to dedicate an entire special double-sized issue to retconning away a previous retcon.
Back at DC, the revamp of Firestorm in the late '80s when John Ostrander took over. This was the start of the idea of the "Firestorm Matrix," and culminated in the character going from nuclear man to fire elemental. Oh, and by the way, the nuclear power plant explosion that fused Ronnie Raymond and Martin Stein? That was not just fate, not just a coincidence. You see, Stein was singled out to be the "true" Firestorm/Fire Elemental all along!
Which led to Ronnie and Mikhail Arkadin leaving the Matrix and Stein entering it to bring Firestorm to his "pure" form to fight the villain Brimstone. Raymond would later return as "classic" Firestorm in the '90s with Stein as Elemental Firestorm as a separate character. Then when Jason Rusch became Firestorm, Stein returned somehow in humanoid form.
The fastest turnaround in retcon history may appear in Uncanny X-Men Annual #2. Serving as both a prequel and installment to Dark Reign, it does away with Namor being presented as a skeevy, smelly, creepy old man by turning the dialogue between him and Emma subtly flirtatious.
Wolverine's claws originally appeared to be part of his glove, so the revelation that they were part of his body may or may not be considered a retcon. Later X-rays of his arms clearly showed that the claws were implants with mechanical housings and an extension/retraction mechanism. When it was later "revealed" that his claws were a natural part of his skeletal system, the conflict with the earlier x-rays was never mentioned. (This includes his original entry in The Official Handbook of the Marvel Universe.)
Similarly, Wolverine's eternal rival Sabertooth first appeared in Iron Fist as a psychopathic human murderer who wore clawed gloves.
In his early X-Men appearances, Wolverine's skeleton was said to be reinforced with strips of adamantium. The current incarnation has the adamantium fused throughout his bones at a molecular level.
In issue #34 of Deadpool, it is revealed that Deadpool is not actually Wade Wilson, but stole the identity from the man who would become T-Ray. This was later retconned in such a senseless, ham-handed way into a trick by T-Ray to mess with Deadpool's head that most fans didn't even remember it until it was restated in Cable & Deadpool.
Despite the fact that Cassandra Cain's entire upbringing was a never ending training from hell, she did love her father, and yet she ran away from him. The reason was that her first kill was the very first time she had witnessed death up close and due to her body reading abilities she thought it to be very, very, scary. Thus she found out her upbringing was evil. Now enter the last issue of Adam Beechen's mini series about her where it is revealed that she hated her dad all along, and that she had actually witnessed her father committing murder up close many times before her first kill.
A rather controversial retcon happened in the Green Lantern series. When DC wanted to reimagine the series, Hal Jordan (the Green Lantern) pulled a Face-Heel Turn and became a super-villain named Parallax, who killed all the other Green Lanterns. Then, he turned back to Face in time to sacrifice himself to save the world. After this, Hal was replaced by Kyle Rayner. Kyle brought an upswing in sales for the book for some time, but eventually DC decided to bring Hal back. In order to smooth over his Face Heel Turn with fans, it was revealed that he never was actually evil, he was possessed by a cosmic being of fear named Parallax.
This change was also another entry in the long list of retcons of the Green Lantern's "yellow weakness." First, Green Lantern was weak against the color yellow because of a necessary impurity in his power, then it was revealed that the restriction wasn't necessary at all, it was something artificial the Guardians imposed on the Green Lanterns to keep them from going power-crazy. When Kyle became the only Green Lantern, the yellow impurity was removed. In Green Lantern: Rebirth it was retconned so that the yellow impurity was caused by the alien entity Parallax being trapped inside the Central Power Battery that gave all the Green Lanterns their power, and Kyle didn't have the yellow weakness because Parallax had been set free by Hal. Since then, the current manifestation of "the yellow impurity" is that the Green Lantern can only use his power against the color yellow if he knows the (most current retconned) source of the yellow impurity, and consciously overcomes his fear.
The character of Peter Quill aka Star-Lord has been subject to a number of different retcons in order to make his origin somewhat comprehensible in the wider Marvel Universe. The original Star-Lord stories took place Twenty Minutes into the Future and possibly in an Alternate Universe, which was slightly reinforced in an Inhumans mini-series which established Star-Lord's father as part of the present day Marvel Universe, with the implication that Peter wasn't even born yet. This was thrown out the window during Annihilation, which tried to position Peter as part of the current Marvel Universe while keeping his original 70's origin. Finally, Brian Bendis just said "Screw it" and started over from scratch, establishing an entirely new (and more coherent) origin that contains bits of the various retcons, but firmly established Star-Lord as a present day Marvel character.
Star Wars: Jedi vs. Sith is basically an official Fix Fic that fits together disparate elements from the Prequel trilogy that conflict with the original trilogy (1,000 years vs. 1,000 generations for the Republic), elements from the Prequel trilogy that conflict with each other, the Valley of the Jedi from Dark Forces: Jedi Knight, some novellas that were in part themselves retcons for the Dark Forces saga, among other things.
A rather controversial retcon by the same author as the Green Lantern example was in The Flash: Rebirth. Barry Allen came back (which was fine) but now instead of the previous "Happy Family" he had, his father was accused of the murder of Allen's mother. Really it was Professor Zoom, who went back in time and killed Barry's mom to ruin Barry's life.
Another Flash Retcon involved Wally West asking Specter to erase the memories of his identity from everyone on earth after the new Zoom tried to kill his wife. Specter did this but left a loophole so that certain characters would remember everything when Wally took his mask off or put it on in front of them. His wife left him for a while, but came back at the end of the arc. Hilarious in Hindsight when you realize it did the same basic thing Brand New Day set out to do (Make their identities secret and make them single, not that the last part was a reason for doing the Flash arc) and did it better.
A particularly controversial example was Steve Engelehart's retcon of The Falcon's origin in Captain America. When the Falcon first appeared, he was a kindly young social worker who became a superhero to help Cap fight off a group of exiled war criminals. Then Englehart came along and decided that before he put on a costume, the Falcon had actually been a violent, drug-dealing pimp who only became a hero because the Red Skull had brainwashed him in order to have a Mole in Cap's confidence. There's a reason it's listed under Unfortunate Implications...
In the Disney Comics, The Phantom Blot's identity was retconned to be a complete mystery. In the first issue he appeared in, not only was his face seen, but his face resembled Walt Disney. Arguably, this was a good decision, giving the Blot an air of mystery.
Deconstructed in Cary Bates and Greg Weisman's post-Crisis relaunch of Captain Atom for DC, in which the eponymous hero (Anti-Hero? Protagonist?) has one origin, which the military covers up, instead publicizing a "false" origin, which was Cap's pre-Crisis Charlton Comics origin. Later on, when Cap lost his powers temporarily, he wore the costumes that he had worn in the Silver Age, because, after all, the public in-story would be familiar with those costumes, having been told he used to wear them.
When the 3.75" G.I. Joe figures first sold, GI Joe was envisaged as an American anti-terrorist task force. When they were made available in the UK, they were sold under the name Action Force. They were accompanied by a comic of the same name which established that Action Force was an international anti-terrorist organisation, of which GI Joe was the name of the American branch.
DC's 1991 event Armageddon 2001 turned out to be a huge mess at the end of the day (isn't it always?) and a major source of Character Development for one Hank Hall (Hawk of Hawk and Dove), which continued through Zero Hour until his death in the pages of the 2000s Justice Society of America relaunch. It also had the nasty effect of unceremoniously killing off the second Dove (Dawn Granger) in a cheap shock scene. However in the later pages of JSA, a big retcon by Geoff Johns would unfold: The woman who the JSA thought was a comatose Lyta Hall turned out to actually be Dove disguised by Mordru in some strange concealment spell (apparently they had to retcon Lyta to Dove at the time due to some issue with Vertigo too). The retcon was successful or not, as the explanation was quite convoluted and Squick: Monarch did not actually kill Dove, Mordru simply made an illusion to make Hawk think she was dead. Then Mordru possessed Hawk and made him rape the comatose yet still aware Dove, impregnating her with his child. So Dove was kept concealed and pregnant for who knows HOW long until she was found by the JSA, disguised as Lyta for some reason who was disguised as yet another woman, and yet she winds up strangely calm and relatively unaffected considering that she was raped and put into such a situation. And the baby? Wound up being a reincarnated Hector Hall. Not surprisingly, little reference has been made to exactly how Dawn cheated death ever since, she just did.
After her return, Dawn then mysteriously gained a younger sister named Holly, however this change was received even worse due to it contradicting various things in the '80s Hawk and Dove series, including Dawn being an only child and the powers being unable to pass on to anyone else. Unsurprisingly, Holly wound up becoming C-List Fodderdown the line as it seems no writer could figure out what exactly to do with her or how to portray her.
The Marvel Comics Micronauts were inexplicably brought back to life in a 1996 issue of Cable. This was exactly ten years after they sacrificed themselves to create a Genesis effect that completely restored their ruined Homeworld into a new world at a natural state. In Cable, Homeworld is inhabited by Psycho-Man who is using Baron Karza's old body banks to create dog soldiers.
Commander Rann, Mari, and Bug are now the only Micronauts. For licensing reasons, they are now called called The Microns; the others having died in war (Marvel no longer has the license to use Acroyear and most of the others. Huntarr's absence is baffling since he was created by Bill Mantlo, the writer of the first Micronauts series).
Homeworld is once again an overpopulated technometropolis and the Microns are freedom fighters. Homeworld is again under the iron fist of someone who probably has to remain unnamed due to licensing restrictions.
In a never released story (again due to licensing), Baron Karza and Thanos have a fight which merges all of the Microverses into one ,so now Sub-Atomica and Jarella's Homeword are now in the same dimension.
Rann and Mari's appearance and personality are different in every re-appearance. In Cable, Rann is buff and heroic looking while Mari's look screams butch lesbian. And she seemed to have given up the swords for normal futuristic weapons. Then Rann and Mari are looking like their old selves in Captain Marvel, although they don't do much more than talk (kind of like a typical episode of Star Trek TNG). In Realm of Kings: Son of Hulk Rann now sports a goatee and reading glasses. And unlike in Cable where Mari had about three lines between the two issues, she's back to her usual verbose self but now talks like an average Earth bimbo instead of a Homeworld Princess. And look at the man legs on her.
Bug is now a member of the Guardians of the Galaxy and for some reason, he's normal human sized and not about 3 inches which is normal when Microversians travel to the regular Earth universe. Rann and Mari (who is once again inexplicably letting others call her Marionnete) have a robot sidekick named Carl (don't ask me) and their latest enemy is Son of Hulk. They journey's around the Microverse aboard the Endeavor III (which sports the most insanely stupidest ship design ever seen in print or screen: a giant atom). It looks as if someone really hated the deeper, more cerebral Micronauts: The New Voyages.
At least in the Marvel Universe this kind of things can be easily explained away thanks to their * infinite* number of alternate universes. It is entirely possible that the current Micros are just not the originals and that they're as confused as to whom they're dealing with as the heroes are.
Stephanie Brown died at the end of War Games as after she was tortured by BlackMask, Leslie Thompkins withheld vital medical treatment. Her autopsy photos were shown to prove the dangers of crime-fighting to Misfit. Batman never had a memorial case for her because "she was never really a Robin". This wasn't a very popular decision. Except she never died: Leslie faked everything because her secret identity was compromised, her body was switched with an overdose victim with a similar body type, and Batman knew this all along. Here's Shortpacked!on the last one.
In the Flemish "De Rode Ridder" series, based on a series of books of the same name, album 131 provided a retcon of the meaning of the title: for about 64 books and 130 comic albums, it had been thought that the title referred to the nickname of Johan the protagonist "The Red Knight", based on his red tunic, 130 revealed that actually Johan was the "Rode" Knight because he belonged to the family of the historical(!) Lords of Rode.
Marvel: The Lost Generation is a twelve issue miniseries built entirely around retcon - specifically, filling in the blank in Marvel history from the 1955 to 1961.
As revealed in the 1980s title Monster Hunters, minor 1940s Marvel speedsters Hurricane and Mercury were both Makkari of The Eternals under assumed names.
On the other hand, Agents of Atlas eventually revealed that the Golden Age heroine Venus is, contrary to previous portrayals not the goddess of the same name. Aphrodite was not amused.
The French comic series Dungeon The Early Years provides one of the best Retcons ever so far. In the very first issue of this Funny Animal gritty comic, the Dungeon Keeper has a look at a picture of his lost love who looks human. Then, in a prequel album, we see her alive under the traits of a snake. Then the authors showed a portrait painter picturing a bird lady as a human and explaining "it's a style that people like these days".
As noted, DC's All-Star Squadron is the Trope Namer. A book in the '80s, set during World War II, introducing a never-before-mentioned over-arching superhero group. It filled in a LOT of gaps in the continuity of the time, picking up dangling threads and plot holes (Why didn't Spectre & Superman just end the War? for example), and reviving many long-forgotten characters. Writer Roy (& Dann) Thomas had to work a little harder when Crisis on Infinite Earths hit, but still continued with Young All-Stars.
Originally, Nightmare Moon was portrayed to be a Superpowered Evil Side of Princess Luna, then the comic changes it so that Nightmare Moon was the product of the Nightmare forces possessing Luna, though this retcon is based on a Word of God from Lauren Faust saying that Nightmare Moon was brought about via an force separate from Luna.
Geoffery St. John of Sonic the Hedgehog was retconned from the son of the king's guard who hated Overlanders for killing his father to the son of the king's guard who partnered himself up with Ixis Naugus in an attempt to free him and overthrow King Acorn for allowing this to happen. It also retconned his choice of people for King Acorn's Secret Service from "the best people for the job" to "people with questionable pasts that he could pin the blame on should he get caught". It's said that he genuinely loved Hershey the Cat, married her and abandoned the plan, but when she was killed off-screen, it pushed him into the Despair Event Horizon and back into the plan.
Sally's various hair/fur coloring was retconned to her falling into a vat of chemicals and subsequent washings changing the colors.
The New 52: Just a year in and they're already contradicting themselves. Teen Titans had Tim Drake mention his time as Robin and that there had been prior versions of the Titans. When the trade paperback came out, this was revised with Tim always being Red Robin (never regular Robin, though still Batman's sidekick), and omitting mentions of prior Titans.
The Titans were also originally referenced in the Batwoman series, with Flamebird claiming to have been part of the team and having fought Deathstroke. This dialogue also found itself edited when it came time for the trade paperback to be released.
A common occurrence in fan fiction if the author discovers they have written themselves into a corner or wish to change something they had previously written. There are generally three approaches to this: Rewriting all chapters involving the retconned material and requesting readers reread the story; having a character in universe explain away the inconsistencies; or placing an author note stating how the events have been modified.
The entire genre of the Fix Fic is intended to create retcons of canon so as to "improve" what the author thinks are issues in the original story. Whether these are actual improvements depends on many factors.
In Mega Man: Defender of the Human Race, the Special Edition Episode 1 makes it clear that the company Wily failed to get a job at was Vick-Tek; in the original it was an unnamed company and mentioned in passing.
It also has Lynn Wersching and AL-05 appear earlier as they investigate Wily's home.
In a rare in-universe example, the Lemony Narrator of the essay-fic, Equestria: A History Revealed, crosses out sentences from sources she cites as soon as they disagree with something else she's been saying. It only points out her alterations of history even more.
Films — Animated
Before 1985, there was no such thing as a set Disney Animated Canon. There were Disney classics of course, but the list of what constituted an "official" entry was constantly changing; they'd add and remove films depending on whether or not they wanted to bill their latest film as "our 15th feature" or "our 20th feature". That changed with the release of The Black Cauldron, which they billed officially as their 25th film by only including films that had at least 75% animation. However, two fully animated films that the list did not include (that had been included in the list's previous incarnations) were The Academy Award Review of Walt Disney Cartoons (1937), which was a compilation of various Silly Symphonies shorts in order to get audiences excited for Snow White and the Seven Dwarfs (1937), and Music Land (1953), another compilation film that featured shorts from Make Mine Music and Melody Time stitched into one film, complete with a new opening and transitions between the shorts. Academy Award Review was re-released into theaters in 1966 and released on Laserdisc in Japan in 1985, but Music Land has been lost to history.
Disney edited the canon again in 2009 by including Dinosaur (2000), which up until that point had not been included, in order to call Tangled (2010) their 50th animated film.
The 2011 Winnie the Pooh film did so poorly at the box office that in some countries (such as the United Kingdom) it was removed from the Canon entirely.
Kopa, Simba and Nala's son mentioned in the storybook The Lion King: Six New Adventures, was ditched and replaced with Kiara in the sequel to The Lion King without explanation.
Averted in this case since the series was published by Grolier Enterprises with the permission of the Disney Marketing department, rather than by Disney itself. The presentation scene however is retconned, and there are several other characters who are borderline retconned (depending on whether you consider the deleted scenes canon).
The Kung Fu Panda 2 tie-in short Secrets of the Masters completely changes the backstories of masters Ox, Croc, and Thundering Rhino, though this isn't too big of an issue since their original backstories were only explained on the official website, not in the film itself.
Films — Live-Action
Madeline, apropos of nothing and in complete contradiction of the books the movie is ostensibly adapting, depicts Madeline as an orphan. Episodes of the Animated Adaptation made after the movie make this change as well.
An interesting example occurs in the film version of The Bourne Ultimatum: At the end of The Bourne Supremacy, Jason Bourne calls CIA Deputy Director Pamela Landy, who reveals his real name, birthdate, and birthplace, before they arrange a meeting elsewhere in the city. This exact same scene occurs in the middle of Ultimatum, after we learn how she came across this information, before we learn that 1) the meeting was a diversion so Bourne could break into the CIA's headquarters and steal the documents he needed, and 2) the "birthdate" she gave him was actually a code for the address of the CIA facility in which Bourne was trained.
This semi-twist has generally been referred to as "awesome" or thereabouts.
The Star Wars prequels introduced a number of problematic contradictions:
In Episode VI, Leia tells Luke that she remembers her real mother; however in Episode III, we see that her mother (Padme) dies shortly after giving birth to both twins — thus either presenting a serious retcon, or else making Leia the most amazing infant-prodigy known in terms of early-childhood memory (particularly since Luke was born first, but remembers nothing).
Alternatively, having lived with the Organas all her life, she considers them her "real" parents, if she even knew she was adopted. Leia remembers her mother as being "very sad", which refers to her adopted mother, because Padme was more "screaming in pain" when Leia was alive.
In Episode IV, Obi-Wan mentions that Anakin wanted Luke to have his lightsaber when he was old enough. However, unless Obi-Wan heard Anakin screaming something very different than what was said onscreen as he was being roasted alive on the shores of Mustafar, this is altered quite drastically in Episode III. Though some fans shrug it off with it being From a Certain Point of View (it certainly would not be the only lie Obi-Wan tells Luke in this scene). Or a bit of wishful thinking ("If he'd known you existed, and if we hadn't been enemies at the end...").
Leia mentions in her message to Obi-Wan that he served (her) father during the clone wars. Except her father was a Senator by that point, and while Obi-Wan was leading the Republic's armies as a Jedi General, he never was in the service of Bail Organa. He did serve Leia's biological mother as a bodyguard however.
This is probably referenced near the end of Episode III, where Bail Organa helps Obi-Wan and Yoda out in their attempts to eliminate the Sith, and later the hiding of the twins.
Averted. It all depends on how you interpret the phrase "served under". He was a part of the Republic's grand army, held rank in it, and the Senate was ostensibly in charge. Besides, when you tell children about who you served under, you aren't really going to tell them all the technical details, and go over the whole chain of command with them. Also, even if she knows the whole thing, Leia is not going to waste message time by going through all the little subtleties of their relationship. Being a diplomat, she should know how to keep a message short and to the point when it's got to be.
In turn, the Star Wars Expanded Universe also features innumerable amount of Retcons. However, they are generally very subtle, used to explain minor discrepancies. Though a few of them are still significant enough to affect ongoing storyline. On the other hand, many are almost something of a Butterfly Effect - a fairly small and seemingly insignificant thing that ends up causing lots of Fridge Logic in other works (or even the same one). In many cases, this is more due to a build-up of lots of these little inconsistencies that magnify each other when combined. Of note is the retcon that Palpatine and Thrawn knew the Vong where coming and told no-one.
The countless species used to have this happen to them on a fairly regular basis. Retcons would include everything from a character formerly established to be one species being retconned into another one or a subspecies, to the appearance of a race changing from one work to another.
Bothans, for various reasons, have had their appearance change somewhat frequently. They originally looked like humans with fur, then like bipedal orangutans, but now look something like a cross between a lion and a kangaroo, with humanoid build. And half-Bothans, for some reason, have hooves.
R2-D2 flying. Apparently, they decided that was too cool an ability and removed it sometime between III and IV.
The Reveal towards the end of Lethal Weapon 2 that the death of Riggs' wife was no accident but rather a botched attempt by the villains to kill Riggs himself back when he with Narcotics working at Long Beach.
In Jurassic Park, the T-Rex didn't eat Dr. Grant because it couldn't see nonmoving objects (in the book, this was in fact a result of splicing dinosaur DNA with frog DNA). In the sequel, this was retconned to rather be that Grant's theories on the T-Rex were wrong, and in fact it ignored him because it wasn't hungry.
Lampshaded in Misery, where Annie refuses to accept the first draft of Paul's new Misery novel because it contradicts known facts — and as his "#1 fan" she knows the books better than he does.
Hey, remember when Kyle Reece told Sarah Connor that "There is no fate but what we make for ourselves?", in the first Terminator movie? Yeah, me neither, but apparently that was the most important thing in the message he was supposed to deliver to her from John Connor in the future, so the second film makes sure to make us remember he said it, as this idea is a big part of the plot of Terminator 2.
At the end of Rocky, Apollo Creed tells Rocky that he has no desire for a rematch. Cut to the beginning of Rocky II (which takes place that same night), and Apollo is so desperate for a rematch that he tries to get Rocky to fight him in the middle of the ER they were taken to for treatment.
As stated in the page quote it isn't just the Highlander series that had a lot of retcons between it in the film, even most of the Highlander films had retcons between them.
In the 1995 miniseries adaptation of Pride and Prejudice, Wickham says "There's one lady I shall be very loath to part from," while looking meaningfully at Lizzie, shortly before he leaves for Brighton. After he elopes, we see this line again in a flashback, followed by a meaningful look at Lydia, which definitely was not there the first time.
In the American remake of The Ring, Samara was a biological child of the Morgans (at least Anna) note This is shown in some medical documents., yet they claimed she was adopted, possibly to hide her supernatural origin. In the sequel, though, it turns out she actually was adopted by them.
A Series of Unfortunate Events: So heavy that a number of companion books had to be written to fully explain them; these were themselves retconned. Handler originally thought the series would only last a few books, not the intended 13, and hence the first four books were essentially unconnected; V.F.D. was created as an ongoing plotline when it became clear the series could run 13 books, and details from the first four books were retconned to be part of the V.F.D. backstory to bring the entire series together.
Discworld, by virtue of being a Long Runner, has a few discrepancies (including when the books actually take place) between the earlier books (such as Wyrd Sisters) and the later ones. Then Terry Pratchett went and Justified it all in Thief of Time by explaining that the history monks just take any time they need and dump any leftover time they have into the ocean. Then there's also the matter of alternate histories. . .
Discworld history had actually been shattered by the trapping of Time, creating the discrepencies.
In a bizarrely creepy in-universe example, this is actually how the Auditors of Reality COMMUNICATE. They don't talk, they just subtly change the past so that they HAD talked.
The example from the Discworld novels is the way the key scene in Mort where Mort and DEATH fight a duel is revisited in Soul Music to incorporate the unseen presence of Susan Sto Helit (stepping back to a past before she was born, in order to discover why DEATH spared her father's life)
Early on, Jill, a member of the We ♥ Kids Club, is established as serious and thoughtful; at one point, Dawn describes her as being like Mary Anne. In the first California Diaries book she is portrayed as very childish, which contributes to Dawn, Maggie and Sunny drifting away from her.
The Brewer children's mother and stepfather are named as Sheila and Kendall in an early book, later retconned to Lisa and Seth when they feature more prominently in later titles.
Similarly, Mary Anne's late mother was named Abigail in the fourth book, but later books identify her as Alma. This is also fixed in reprints.
There was a short spinoff series where each of the girls writes an autobiography. They must have been written by different writers, because Kristy, Mary Anne, and Claudia have conflicting memories of their elementary school years (when they all knew each other).
In the early books, Dawn is a semi-vegetarian who eats chicken and fish; she avoids red meat because she thinks it's unhealthy and doesn't like the taste. She specifically says in one book that her vegetarianism DOESN'T have anything to do with feeling sorry for cows, and in fact she doesn't even like animals all that much. This is somewhat hard to reconcile with the radical enviornmentalist she is in the later books.
Somewhat similarly, the Xanth series began addressing early-book continuity issues by saying the magic-dust madness area was spreading and screwing with reality.
Several in the Star Trek Novel Verse. A particularly good example: in Star Trek: Vulcan's Heart, Romulus' capital was given the name Ki Baratan. It had previously been called Dartha, but that was in a story set a century prior. Later novels used the time gap for a reasonable Retcon: the capital's name changes as new regimes come to power. Now, books set in the 22nd or 23rd centuries use "Dartha", those set in the 24th use "Ki Baratan". The name change is explicitly mentioned in the first Star Trek: Titan novel. Another good example is the Andorian issue. The Andorians were initially portrayed somewhat differently between Star Trek: Enterprise and the Star Trek: Deep Space Nine Relaunch novels, but later books skillfully resolved the seeming contradictions. The various portrayals now add up neatly. Also, in the Star Trek: Enterprise Relaunch, the names of Xindi characters are a blend of screen names and those given in early novelizations. For example, the Xindi known as Dolim was named "Guruk" in the first novelization, so in later books his full name is given as "Guruk Dolim".
In-verse example: 1984 is hugely based off this trope. Big Brother can rewrite history at will, and the masses have to eat it up. Retconning is done at the Ministry of Truth, the protagonist's main place of work, and mainly consists of editing out people who fell from Big Brother's favor and were "vaporized."
In the Honor Harrington series, later books (and short stories, although they are set earlier in the timeline) reveal that Honor is the result of genetic modification that gives her enhanced physical abilities and an increased metabolism. It raises issues about incidents in the early books she's described as accomplishing because of practice, training, and being raised on a higher-gravity world, instead of being inherently stronger and faster.
In the first book, when the story of Pavel Young's attempted rape and its aftermath is mentioned, the resulting stomping of said aforementioned rapist-wannabe is given as due to her martial arts training and world of origin. In Field of Dishonor, the winning of the duel is implied to be due to her rage and relentless practice. It's only well into later books that it's revealed she had a tad more of an edge than just the learned skills.
From the Harry Potter series: in Harry Potter and the Philosopher's Stone, Dumbledore flies to London for a supposed meeting, then flies back, arriving just in time to save Harry from Quirrellmort. We were probably supposed to believe that he was on broomstick. But later books introduce the ideas that wizards have instantaneous methods of travel: Floo Powder, Apparition, etc. Book 5 tells us Dumbledore went on a flying horse (Thestral) because he wanted to arrive late because the Ministry (who were supposed to have called the meeting) were annoying him. But couldn't he have just taken Floo Powder at a later time?
In the first book Rowling had Voldemort tell Harry that his father "put up a courageous fight" before he died, and there was no reason for him to lie to Harry at this point (although it's not inconceivable that he was exaggerating). Seven books on, James Potter is killed in flashback without raising so much as a finger against Voldemort, though James did try to hold him off, but was killed quickly, having forgotten his wand.
Also Rowling made Flint, a character who is said to be in 6th year in the 1st book, remain there in book 3. When asked about this, she said, "Either I made a mistake or he was held back a year. I think I prefer Flint making the mistake."
In an otherwise throwaway line in Quidditch Through the Ages, powerful wizards are said to be able to Apparate across continents. Come Deathly Hallows, however, this is quietly retconned; Apparition is now said to have a range of effectiveness less than that of Western Europe, and even Voldemort is forced to fly "within range" of a certain location before he can Apparate.
The waterfall that separates the first and second precincts of Death is described as "getting louder" when an entity passes through it from the second to the first precinct in Sabriel, but that is retconned in Lirael where an entity passing through causes the waterfall to go silent, and thus agreeing more with the idea that a pathway must be made through the waterfall by magic.
A very confusing retcon occurs in regards to "Gore crows", bodies of dead birds reanimated with a single spirit. They are at first described as extremely dangerous due to many of the birds being able to overwhelm an individual, but later when Prince Sam kills one with his slingshot, the Disreputable Dog claims that the other gore crow, which took turns spying on the main party, would be killed because they are both linked to the same spirit. But if this were true, then the first description would not make sense, as as soon as the individual was able to kill one of the crows, the rest would perish.
There's a difference between making a part of a soul retreat from a body and banishing it to Death.
The Gore Crows died in Lirael because the one Sam shot landed in running water, which is specified as being inimical to the Dead.
The Lestat that appears in Interview With A Vampire is a rather stupid, petty villain with a streak in banal evil. Anne Rice wrote in her later books that this portrayal was merely Louis' spiteful gossip and/or misunderstandings.
If The Vampire Lestat is read before Interview With A Vampire, the impression that Louis is giving the account as a bitter ex-love becomes pretty unmistakable.
In the Jurassic Park novel, Ian Malcolm is very definitely dead. They're even trying to get through diplomatic red tape to get him buried. By the time of The Lost World, Malcolm is alive and well, having only been... mostly dead.
In Stephen King's Misery, psychotic nurse Annie Wilkes forces Paul Sheldon to retcon the death of Misery Chastain in his series of romance novels. His first attempt is to simply Rewrite it, but he is forced to do a Revision in which Misery was buried alive in a coma when Annie considers the rewrite to be cheating.
In the Sherlock Holmes stories, Arthur Conan Doyle originally intended Holmes to die in "The Final Problem" (as the name kinda implies), but the Holmes fans were so furious (there's a story that an old lady screamed "murderer" at him on the street) that in the end Conan Doyle had to Ret Con his hero back to life in "The Adventure of the Empty House". Opinion pretty divided on whether this is a good thing or not: there are some very good Holmes stories after he comes back, but overall the quality does go down, due to Conan Doyle not really caring any more.
Len Deighton's Hook Line & Sinker trilogy retconned the events of his earlier Game, Set & Match trilogy. In the latter trilogy, Bernie Samson discovered that his wife was a deep cover agent for the Russians. The former trilogy changed this so that his wife was actually working as a deep cover agent for the British with her defection as a bluff
The Dragon Lance War of Souls trilogy retcons the role of Chaos, "Father of the Gods" to "delusional god who thinks he's father of the gods."
Not to mention retconning out the ending of Dragons of Summer Flame. Not only does Tasslehoff not die, but Takhsis steals the entire world, somehow pretending to be Fizban while departing with Raistlin. This couldn't have happened, because Raistlin somehow ends back with the gods, a major plot point in Dragons of a Vanished Moon.
Officially, there's now another Chaos retcon. He's an Eldritch Abomination equal and opposite to the Highgod; while not the ultimate creator, the universe was, in a sense, created from him, and he is as far above the gods as they are above mortals.
Another retcon is the conception of Steel Brightblade, which no character knew about until The Second Generation.
Don Quixote. Part 2, which was written a decade after the publication of Part 1, is predicated on the idea that Part 1 was published as non-fiction in his world. This gives the author an opportunity to address contradictions in the original work, by having a character who had read it ask Quixote himself for explanations of what really happened.
The actual explanation for this is that there was a unlicensed second part "Second Volume of the Ingenious Gentleman Don Quixote of La Mancha: by the Licenciado (doctorate) Alonso Fernández de Avellaneda, of Tordesillas" written that directly insulted Cervantes. It ended up serving as the impetus for Cervantes' Part 2, and there are many jabs, both direct and indirect, at this spurious sequel, in Cervantes' own sequel.
The Hobbit was written well before J. R. R. Tolkien came up with the plot for The Lord of the Rings. In the original story, Gollum's wager for the Riddle Game was a "present", which turned out to be the ring. Once The Lord of ohe Rings existed, having Gollum ever do anything which might lead to him losing the Ring suddenly made no sense at all, and so that chapter had to be Ret Conned. Tolkien dealt with it by making Bilbo an Unreliable Narrator, and having Gandalf shake the "true" story out of him during The Lord of the Rings.
The character of Elrond is also slightly different from one book to the other: when Tolkien wrote The Hobbit, he gave him the name of Elrond, which he had previously used in drafts of The Silmarillion for the son of Eärendil, but did not make him the same character, which is why it isn't clear in The Hobbit whether Elrond is actually counted among Elves - he appears to be a Man. It was only when writing The Lord of the Rings that Tolkien explicitly made the character that appeared in The Hobbit, and the character that appeared in The Silmarillion, one and the same. (Some have argued that this creates another problem, since Elrond, a descendant of Turgon, should perhaps have laid claim to his great-grandfather's sword.)
Though not much use a Sword would be to Elrond anyway, and it's likely Elrond figured Gandalf would need it more. At least it explains how Elrond knew what Glamdring was so quickly.
Though Tolkien had been working on the myths of Middle-earth for a long time, The Hobbit was not originally set there when it was written, so the earliest editions contain things that were later eliminated, like references to policemen.
If you're interested in studying Tolkien's languages, the many changes and revisions in the linguistic history across Tolkien's life can be a nightmare. Many of these changes are "internal" (not in texts intended for publication, so not proper retcons), but a lot aren't. In fact, most "corrections" to the second edition of LOTR were linguistic in nature. Other changes involved names that weren't updated as the languages changed: the name Fëanor initially was pure Sindarinnote Called Noldorin back then. for "spirit of fire"; but decades after, the pure Sindarin form would have been Faenor, and the name had to be explained as a mix of Quenya and Sindarin.
In The Odyssey, there are two sirens. Yet there is art that depicts three. How to fix, how to fix — obviously, one of them committed suicide in a rage after Jason and the Argonauts! And another one after Odysseus got away! (Which raises the question of how the third one died. . . they never did settle that.) Older Than Feudalism.
Arthur C. Clarke's 2001: A Space Odyssey directs the fateful mission to Saturn, but The Film of the Book goes to Jupiter (according to The Other Wiki, because the special effects team couldn't make a satisfactory ring effect for Saturn). When Clarke wrote 2010, he decided that Jupiter worked better for the new plot and went with it.
3001: The Final Odyssey retconned the events of the first 3 books to occur at a later date. 2001 was changed to 2015, with 2010 and 2061 getting a respective forward push, as well. (It was written in 1996, by which time it was pretty clear that Clarke's 2001 would not happen.)
Word of God — erm, I mean word of Deus — is that each book takes place in a slightly alternate continuity from the others. Which explains Dave/Star Child's Badass Decay between 2010 and 2061, and Floyd not appearing as part of the Dave/HAL/Monolith entity at all in 3001. Some people still find this incredibly lame.
Since the Cthulhu Mythos has had so many authors over so many years, lots of stuff gets retconned back and forth. Particularly notable is August Derleth's [oft-reviled attempt to impose Elemental Rock-Paper-Scissors and a good/evil dichotomy on Cosmic Horror and fans revising the wings of Elder Things and Mi-Go (which were originally said to allow them to fly through space) to solar sails.
The Sword of Truth series: Presumably to explain the inconsistencies in the timeline generated by the official version of the Magic of Orden, the final book reveals that the Book of Counted Shadows, supposedly the instruction manual to safely use the power of Orden, is a fake So far, so neat and tidy, until you remember that the climax of the first book and a large chunk of the plot of the second book (and, indirectly, most of the rest of the series) rest on Richard awakening his Gift by using it to kill his father - by tricking him into opening the wrong box - which doesn't apply if there never was a right box, meaning Richard's Gift should not have awakened. Not that the logic was entirely convincing to begin with...
In Animorphs, Ax is at the beginning unable to communicate in thought-speak while in human form, explained by the fact that humans cannot use thought-speak. Later in the series, Ax repeatedly uses thought-speak while in human morph, because it is, after all, a morph.
In the first book, Jake can communicate in thought-speech with Tobias when he's in a morph and Jake isn't, which would have come in really handy for the characters later. K.A. Applegate intended to take that scene out, but forgot.
An in-universe explanation popular in some fanon circles is that humans possess a vestigial capacity for thought speak similar in function to the Andalite sense of taste. Neither Human nor Andalite scientists ever noticed it and the Yeerks weren't interested, but it helps explain why humans innovate so quickly. Under this explanation, the above example worked the way it did for three reasons: Jake has a strong personality and is unusually able to 'project' his thoughts, Tobias has a sensitive personality and is unusually able to 'hear' thoughts, and both of them expected it to work - but since it didn't work for anyone else, they both later thought they were imagining it.
An in-universe example: in The Chronicles of Narnia: Prince Caspian, the "history" under Miraz' rule is described as "more dull than the driest history book you have ever read, and less true than the most exciting adventure story."
In a strange retcon of the events of the Trojan War, some poets contend that Helen never actually went to Troy and that Paris instead was tricked into abducting an illusion of her (don't ask). In another retcon, Helen is carried off by Paris but ends up being stranded in Egypt. Euripedes reconciles these two variations in his play Helen. He also rewrote Trojan War history with his Iphigenia plays, crafting a scenario in which she survives the efforts to sacrifice her to the gods and has various misadventures while her father is off to war.
The prequels to the Belgariad and Mallorean books do this to several different plot points. The most egregious example is that taking into account Silk's cameo towards the end of Belgarath the Sorcerer, when he and Garion encounter Asharak in Pawn of Prophecy, Silk should have recognised Asharak on sight, should have known that "Asharak" was one of Chamdar's aliases, and should hence have realised that the fact that Asharak was poking around was highly significant and should be reported to Belgarath immediately. It's handwaved with the implication that Asharak was tampering with his mind, but that still doesn't explain why Belgarath didn't react to the name.
The first book of the GONE series has Michael Grant (author) toy with giving Astrid a power, in which she is stated to be a quasi-powerful freak with the power to tell if someone is "special" or "Important". As of the third book however, Astrid is explicitely stated to have No powers and her mutation is never mentioned again.
Michael Grant has stated in three interveiws that he regrets putting Astrid's power in as A) he didn't think her power was interesting,useful or original and B) he wanted some of the main characters not to have powers to break the status quo a little.
Fans are still debating whether he was right to cut the mutation out however, with some fans arguing that her power didn't add much to the plot and that Astrid is already described as being beautiful and a genius, so giving her powers would make her a Mary Sue. Other members of the fandom however argue that it's unrealistic (due to genetics and such) for her brother to be the most powerful freak in the series and for her not to have a power at all. They also think her power should have been kept in to avoid plot holes, and well, a retcon. And that's just one of the many ways Astrid is a BaseBreaker
No two versions of The Hitchhiker's Guide to the Galaxy (radio series, books, TV series, movie, ect) are exactly the same. And contrary to many fans misconceptions, the books are a retcon of the original radio series. Douglas Adams has stated that this is intentional and there is no one canonical version of the story.
The Malazan Book of the Fallen underwent significant changes in backstory between when Gardenofthe Moon was completed and the initial publication of the Malazan Series. Especially where Steven Erikson dealt with matters relating to The Fall of the Emperor, His rise as Shadowthrown, Cotillion and his rise as sidekick/god of assassins Rope, and the rise of Laseen as the New Empress. As a result, fans of the series have a term for retcons relating to history between Gardens of the Moon and the rest of the Malazan series: "Garden of the Moonism."
Remember when Rolling Stone declared Pink Floyd's album Wish You Were Here to be "actually nothing more than the skillful manipulation of elements so simple — the basic three chords everyone else uses — that any collection of bar hacks could grind out a note-for-note reproduction without difficulty"? Well, neither do they, considering they now declare it one of the greatest albums of all time.
Alias - "Hey you know the man you loved that died and you grieved over? Yeah, know he's alive remember, and we totally knew about it all the time, even though you cried lots in private over his loss." Explainable in-universe, however, since the enemy is dangerous enough to be able to successfully bug even the private homes of the characters for long periods of time before being uncovered. Having experienced that in the past, it would be sensible for that kind of charade to continue in private just to be on the safe side.
The Klingon makeup change was just better budgeting from the show to the movies. Worf's scene in Deep Space Nine in the flashback turned it into an actual plot point.
The reference was meant to be a quick joke about the effects budget in an episode that was already tongue in cheek. The writers expressed total bafflement over how much of an uproar it had created with the fandom. Reactions in Usenet newsgroups ranged from "can't you guys relax and take a joke", to "we demand answers NOW!" to "We were fine ignoring it until you morons brought it up". The same lunacy also made another Worf joke from that same episode, the "The Great Klingon Tribble Hunt", official canon. Canon is serious business.
In the end, Star Trek: Enterprise resolved the matter once and for all, proposing that the change was a side effect to the cure for a fast-spreading plague.
The changes we see in Kang, Koloth and Kor are alluded to as well, as the episode ends with a Klingon doctor speculating on the fortune to be made in the reconstructive surgery business — an option for seasoned veterans who had acquired fame and fortune in their younger days, but probably not for young starship commanders looking to make names for themselves. (And neatly ties up the early version of the Klingon makeup used in Star Trek: The Motion Picture as the result of botched reconstructive surgery.)
Exactly the same thing happened to the Ferengi between Star Trek: The Next Generation and Deep Space Nine, turning from a mighty empire with warships that seriously threatened the Enterprise into a one-note joke race of scheming cowards.
TNG's pilot, "Encounter at Farpoint", implied that the Ferengi were known for eating sentient beings. This was never brought up again.
TNG introduced an entire new race mid-series: the Cardassians. They had never been mentioned before, and yet in their very first episode, it is made clear that the Federation and Cardassians had been at war. And recently enough to be living memory for several crew members. Indeed, the plot of the Cardassian introduction episode is all about the psychological fallout from them. They got a lot of mileage out of this retcon.
And then again during TNG, the Borg changed from assimilating only technology to being essentially techno-vampires.
In the final episode of Star Trek: The Original Series, "Turnabout Intruder", Dr. Janice Lester pulls a Grand Theft Me on Kirk to break through the glass ceiling, because even in the utopian future of Star Trek, women were apparently barred from service as starship captains. This embarrassing piece of 1960s male chauvinism was retconned out by attributing it to the delusions of a mentally unstable woman, despite Kirk's explicit on-screen acceptance of both the accuracy of her accusations, and the injustice of the policy.
The revelation made late in Star Trek: Deep Space Nine that Dr. Bashir is a genetically engineered superhuman causes numerous conflicts with earlier episodes, and basically makes him an awful person through Fridge Logic. For instance, the episode reveals that he could win every game of darts against O'Brien. Not only does this make their entire friendship seem like a farce, since playing darts is the chief activity they're seen enjoying together, but it contradicts the episode "Visionary" where O'Brien's foreknowledge of where Bashir's darts are going to hit was used to show that he had really been to the future. Then the episode "Distant Voices" is centered around an alien probing his mind and drawing out his deepest secrets, but him knowing himself to be the product of illegal genetic engineering never comes up. Taking this further, if one revisits the Season 2 TNG episode "Unnatural Selection", where the Darwin station scientists are engineering perfect humans, those scientists are doing something wholly criminal (by any measure several orders of magnitude worse than what Julian's parents did) and really should have been taken into custody by Picard.
Star Trek: The Next Generation has a revelation that excessive warp speeds are causing holes in spacetime (in an AnviliciousAesop about pollution and the environment), which prompts the Federation to limit ships to Warp 5. Characters in a couple of subsequent episodes pay lip service to the "speed limit" right before they break it, but after that it is forgotten completely, with the general Fan Wank being that an improved version of the Warp Drive that didn't mess up subspace was invented. May also apply to what ought to be the inevitable ramifications of a new technology or application thereof, such as retrieving a heretofore-disintegrated crew member out of the pattern buffers of the transporter. In Peter David's Star Trek: New Frontier novels, there's an offhand reference from a character who can "see" spacetime about the damage still being done by warp travel. This got so noted that fanfiction writers No-Prized it, coming up with the dual ideas of the ruts worn in spactime healing over a period of time and simply changing your routes to avoid cumulative Spatial Fatigue.
In Star Trek: Voyager, The Mole Seska claimed to Chakotay that she impregnated herself by stealing his DNA. She also told Kazon leader Cullah, who she was sleeping with, that the baby was his. After the baby was born and was clearly a Cardassian/human hybrid with no Kazon-like features, Cullah was naturally pretty pissed off, which led us into the season ending cliffhanger. However, between seasons everyone decided that the Kazon weren't up to the job of being the show's big recurring bad guys they were envisioned as, much like the Ferengi on TNG, so they decided to drop them from the show entirely. This involved Seska dying, and Cullah running away with the baby. Naturally, fans wouldn't accept Chakotay's kid being raised by the Kazon, however unwillingly he fathered it, so just before this the Doctor reveals it is actually Cullah's baby after all. The baby's appearance is Hand Waved by saying there's never been a Cardassian/Kazon hybrid before so before now no one knew what one would look like, and it'll probably develop Kazon features as it ages.
The two-part Star Trek: Voyager episode, "Year Of Hell", plays retconning literally. The Big Bad has developed a weapon that lets him use retcons to change the timeline (while he himself is protected by Applied Phlebotinum). He first uses it to reverse a stunning defeat to his species... Only to discover he's accidentally retconned his beloved wife and daughter out of existence. He keeps trying. (Also provides a handy Reset Button: evidently, destroying his ship undoes all his Retcons, and Ramming Always Works).
And then there's the question of currency, specifically whether the Federation uses any during the 23rd century. There is at least one mention of a crewmember "earning their pay" in a TOS episode, though that might have only been a colloquialism Kirk was using. In "The Trouble with Tribbles", we see what clearly looks like trade with a human salesman - it's hard to imagine that guy was just in the business of giving away these critters for free. Then by The Voyage Home Kirk has a quote about people in the 20th century "still using money", implying that they don't anymore. You might think that they stopped using money at some point between TOS and the fourth movie, but the tone and reactions in the scene seem to indicate the Enterprise crew is completely unfamiliar with the concept of currency - so the change wouldn't have occurred in their lifetime. And of course, by the TNG era, they pretty much beat us over the head with the fact that the Federation doesn't use money anymore (except for outside trades with other species, especially the Ferengi). Enterprise seems to hint that currency was abandoned when the Federation was first formed, a few years after the end of that series, but it's very vague about it. And then, to add further confusion, the 2009 movie has a scene that takes place in a bar, on Earth, that clearly seems to operate on capitalistic principles (not to mention the Nokia phone in Kirk's uncle's car). Now, that movie takes place in an alternate timeline, but since the two timelines diverged on the day of Kirk's birth, it would mean that even in the original one, currency was still legal tender at least until that day. To sum it up, it seems like we're now just meant to vaguely accept that they've phased money out by the 24th century without asking too many questions about how they did it or the precise moment when they did.
Trills make their first appearance in an episode of Star Trek: The Next Generation ("The Host"). Here, the symbiont clearly has total control over the host body and considers transporters to be harmful. In Star Trek: Deep Space Nine, the makeup is completely different (mainly because they didn't want to ruin Terry Farrell's looks with a rubber forehead), the host and symbiont create a combined personality, and use of transporters does not appear to be an issue.
In Space Seed, the Eugenics Wars (set during the 1990s) was mentioned by Spock to be in the "era of your last so called World War". In the Next Generation era, World War III is said to happen at least five decades later. Additionally, author Greg Cox, who wrote several Trek novels set during the Eugenics Wars era, observed that the passage of the real 1990s necessitated reimagining the Eugenics Wars as a less overt conflict that happened around real life events and may not have been known to the general public. The episode where the Voyager crew visited the 90s did not depict an Earth embroiled in a world wide conflict with genetic supermen. Cox also humorously noted (in one of the DVD extras in Wrath of Khan) that Khan didn't exactly appear on the cover of Time Magazine.
Parodied in The Conditions of Great Detectives when, in the final episode, Banzo finds out his family has been completely rewritten without his knowledge. Originally his estranged wife was Japanese and a teenage daughter, Hanako who commited suicide. His new wife wants to get back together with him and run a restaurant together, she's also blonde and non-Japanese - and their new daughter (who has another name) is a lot younger and also blonde. Banzo compares the family photograph his "new wife" gave him and compares it to the photograph of the "old family" he carries in his wallet.
Although Scrubs doesn't usually do a lot of continuity, one of the later episodes has a throwaway joke where J.D.'s friends claim that he cannot see women wearing their wedding ring. If that is the case, how was he able to see Carla in the later half of the show (5-9), or T.C.W., for that matter...
Another J.D.-related retcon is that in later season of Scrubs, he says he doesn't like beer. In the earlier seasons of Scrubs, however, he's clearly shown drinking beer in some episodes. Turk eventually calls him on this when he claims he can't drink beer, and he admits that he's been making up excuses to drink appletinis (which is itself a retcon, since part of the gag about the appletinis was that he doesn't even realise other people find it unusual).
Elliott from season 2 onwards can't say dirty words as a result of her mother's influence as a child, making up her own euphemisms. Yet she had no problem saying "penis" and "vagina" in several season 1 episodes.
In the initial mini-series and first few episodes, humanoid Cylons are shown to have glowing spines during intercourse. However, this was officially retconned by producers when it was pointed out that Dr. Baltar already had an amazing Cylon detector. In his pants. Though note Scifi Channel commercials for the second half of season 2, which show a spinally-luminated fetus. Also, in the commentary for later webisodes, writer Jane Espenson mentions it was planned to depict Eight's spine glowing during sex with Gaeta but the scene was rewritten for them to kiss instead. The novelization of the Miniseries says the glow isn't visible to the naked eye, but that book isn't Canon.
In early episodes we learn that human Cylons had 'evolved' from the Centurions after the First Cylon War. Later there are a few hints that human models already existed before the war. Then, in the last ten episodes, it is revealed that the ancients on Kobol first created artificial 'humans' thousands of years ago, and descendants of these same artificial humans had worked with the Centurions to create the new human models.
Several characters are revealed to be Cylons and thus, alive after they and the audience thought for years they were human and/or dead. Stand up Anders, Tyrol, Tigh, Tory and Ellen!
In the miniseries, the audience learns that there are only twelve Cylon models that look like humans. These are gradually revealed over the series, the twelfth and final Cylon in "Sometimes A Great Notion" then, four episodes later we learn of the (former) existence of a lost thirteenth model, whom we never see.
This one is especially bad because when it was first revealed, many fans took it as an explanation for what the hell Starbuck was after being apparently resurrected despite her dead body still being on Earth. Ron Moore was quick to deny this, as it was just thrown in as an explanation for why the number designations for the humanoid Cylons skipped number 7.
In My Parents Are Aliens an episode showing how the aliens met the children shows that Brian and Sophie originally had disguises resembling the presenters of Crimewatch before changing into their familiar forms. Later in the series 7 finale they said that they stole the identities from the children's real uncle and aunt, also named Brian and Sophie.
Doctor Who: Many of the most notable features of the series, such as regeneration and the Time Lords, were retconned in, often to account for some out-of-character problem.
In "The Sea Devils," the Doctor points out that the cave creatures from "Doctor Who and the Silurians" should have, in fact, been named the "Eocenes" instead of the "Silurians," because of the epoch they originated from, which is the real-life author (same for both stories) correcting his earlier mistake when he was called on it after the broadcast of the first story. Also, the doctor was originally supposed to have 13 lives, but it seems that will change. Even the count of which Doctor each actor plays has been retconned, as well as the final events of the battle on Trenzalore. That last one is an in-universe retcon as well.
Uniquely, Doctor Who has had two paratextual retcons during the Tenth and Eleventh Doctor's tenures, consisting of in-universe explanations for the theme song and title.
The episode The Two Doctors was an attempt by Robert Holmes to retcon the early eras of the show. The loosely canonical "Season 6B"—which claims that the Doctor wasn't regenerated at the end of The War Games, but was sent by the Time Lords on various missions around the cosmos—is actually less insane than what Robert Holmes was planning! Robert Holmes figured that it was impossible for the Time Lords to just lose track of a TARDIS, so in reality the Doctor had been working for them from the very beginning! This also explains why the first and second Doctors were never able to control the destination of the TARDIS. Holmes said that after the events of The War Games the Doctor's superiors let the Doctor take the fall for his interference, even though he had been acting on their orders.
Nu Who Series 7 and the 50th Anniversary Special "Day of the Doctor" managed to retcon in an entire new Doctor. When it was revealed that a secret hidden Doctor, played by John Hurt, existed, fan theories melted down the internet (including on this very wiki) as to who he really was. One fan theory that was roundly rejected was that he was the Doctor who fought in the Time War and destroyed both his planet and people and the Daleks as well, thus the epic guilt that caused him to try and forget that persona. The problem there was that the Doctor had spoken frequently about his involvement in the war, and the action he took to destroy both sides, leaving himself as the sole survivor, and the massive guilt he feels. None of that was a secret, so why would the body he used to do it in be one? Of course, once the Fiftieth anniversary special aired, it turned out that that was indeed who John Hurt's Doctor was, meaning that every line of dialogue establishing that Christopher Eccleston's Doctor was the ninth, David Tennant's the tenth, Matt Smith's the eleventh, etc., were all lies that the Doctor was telling so that he could try and forget the version of himself that committed the heinous act that he had no trouble talking about in all three of his subsequent forms. On the other hand, the 10th Doctor's line about regenerating "half a dozen times" since the last time he saw Sarah Jane has a new meaning now: he didn't forget about the events of "The Five Doctors" after all.
"The Brain of Morbius" displays the faces of previous incarnations of the Doctor at one point, including several others in addition to those of the first three Doctors. These were retconned to have been Morbius's previous incarnations just a handful of stories later in "The Deadly Assassin", in which the Fourth Doctor informs Borusa that he's only had three 'face lifts', and in which the twelve-regeneration limit was established.
The Doctor has blue Alien Blood in "State of Decay", but normal red blood ever before and normal red blood ever after.
Season 2 of Heroes has a rather clumsy example. In the middle of the first season, it's revealed that Matt's wife is pregnant. This causes a few fans to wonder if the baby is really his, since she cheated on him earlier in the season. However, in an episode set five years in the future, we learn that the kid is named after Matt, sends him crayon drawings of himself and mommy from hiding, and, most tellingly in a show where almost everyone with superpowers gets them from Super Powerful Genetics, has a power. Then in an early Season 2 episode, Matt says that whoops, turns out it wasn't his kid after all. In "Fight or Flight," a later Season 2 episode, however, it is implied that he has accepted that it isn't his child without any actual proof, when he has a nightmare in which his wife chastises him for not reading her mind and learning the truth, so this may be a reversion more than rewrite.
In S1, Mohinder was originally said to have been two years old when his sister died, but they changed it so that he was born months before she died in order to wrestle Molly into his plotline.
Season 3 retcons Sylar's murderous ways as a side effect of his original ability. His ability to know how things work apparently gave him a "hunger" to kill people just so he can satisfy his fix for more power. This of course ignores that S1 and S2 showed him utterly reveling in murder, even when he didn't have any abilities.
Although it does explain why a socially suave murderer capable of killing someone, turning around and dropping back into whatever character he was playing to manipulate someone else into doing what he wanted without missing a beat would have a Room Full of Crazy stating "Please Forgive Me" over and over, which Suresh encountered in S1.
The writers have a go at fixing this one again, with Sylar shown to have gone through a guilt ridden phase around the time the series began, presumably redecorating appropriately.
Take it as a retcon or a further loss of his humanity, but as of season four Sylar can seemingly suppress his hunger (evidenced by a casual road trip that lasted for several episodes next to tasty brain Luke) but still revels in his murderous behavior, perhaps moreso.
The plot that tried to explain this retcon also retconned Elle's background, as she is portrayed as relatively normal and even caring and guilt-ridden, rather than sociopathic and murderous as in season 2. This contradicts season 2, in which she states she was diagnosed as a sociopath at eight.
The first one noted above was settled once and for all in volume 4, where it's confirmed that the baby is Matt's.
It seems that every other episode that something new is added to Noah Bennet's back story that wasn't there before. A prime example in season 4 when we see that Noah almost participated in an affair during the events of season 1, when his daughter was in danger. Then later in the season, we find out that he had a deceased wife that had never, ever been mentioned in the plot before.
Claire having magic blood in Series 2 which can resurrect anyone from the dead, such as when Noah Bennet was killed after being shot in the eye. This is promptly forgotten after this incident and by Series 4, when her biological father Nathan is killed, reviving him in this way is never an option.
The actual cause of what gives them powers has also been retconned several times. At first its hinted at being a genetic trait which has something to do with the brain. This made some semblance of sense, until an Eclipse somehow turned everyone's power off. And then Hiro's mother had some kind of mystical power that was the key to abilities... or something?
There's also Sylar's parentage. When we first meet him, he tells us his parents were ordinary people (indeed, they're too ordinary for him). It's later revealed that he's adopted, and that his real parents are Angela and Arthur Petrelli. This is later retconned too, and it's revealed that his real father was an evil psychopath that killed Sylar's mother.
Sabrina the Teenage Witch establishes that the curse that will turn Sabrina's mother into a ball of wax is only supposed to last two years - so it should lift when Sabrina turns eighteen. Yet in the sixth season (where Sabrina is 20-21) it's still in effect. And when they go to the Witches' Council to appeal, none of them mentions that the curse should have expired by now.
Season 3 shows that cousin Amanda has a little sister Allie. She's never mentioned nor referenced after this.
In Charmed the sisters constantly had to fight the risk of exposing their magic to the public. The season 3 finale revolves around them trying to get a demon to turn back time for them to reverse this. But season 6 adds in entities called The Cleaners whose job is to fix things whenever magic is exposed. They claim they've been watching the sisters from the beginning. They would have been really useful three years ago.
The show plays with and subverts this trope in a very interesting way within the show. In the end of the first episode of season 5, Buffy suddenly has a sister that has never appeared or been mentioned before, and it had previously been established that Buffy is an only child. But neither Buffy nor anyone else shows any signs that anything is out of the ordinary. It later turns out that powerful magic was involved that not only created Dawn, but also retconned her entire past life into the memories of the people of Sunnydale. Even when it turns out she didn't really exist until some months ago, she continues with her current life as if she were a regular person.
In season 1, Giles states that he is inexperienced with magic and has never used it before. By season 2 it has been established that while he was in college he was using magic recklessly enough to gain the nickname "Ripper" and to summon a dangerous demon that killed several other people.
Also done well in Spike's introduction. He expresses anger that Angel has gone good, saying, "You were my sire, my Yoda, man!" Angel doesn't elaborate on this at the time. Later we learn that it was Drusilla who actually turned Spike into a vampire while Angelus was his teacher and role model. In another episode Spike outright says, "Drusilla may have made me a vampire, but you made me a monster." Joss Whedon also gave the explanation at one point that 'sire' can refer to any of the predecessors of a vampire's line and not just immediate sire.
Spike saying that he respected Angel. Flashbacks show that he and Angel were always at each other's throats.
Both Spike and Angel had their ages changed. For Spike it happened twice. He went from "barely 200" in School Hard, to 126 in The Initiative, to 120 in Fool for Love. Angel had 29 years added to his age in the episode Becoming.
A minor example concerning Anya's demon friend Halfrek. She was played by Kali Rocha who had appeared in another episode as Cecily, one of Spike's human love interests. In her next episode when she and Spike appeared on screen together they had Halfrek say "William?" and then the two avoided each other's gaze, implying Halfrek and Cecily to be the same person. Also Halfrek's flashback scene in "Selfless" was changed from the Renaissance to the Russian Revolution to support this.
Throughout the series it is firmly established that Sunnydale is the center of all evil activity (thanks to the Hellmouth) and has been for a long time. However, in the first season, no one in town (including Willow, Xander and Cordelia) seem to be aware of the existence of vampires and demons until Buffy shows up. Whedon tries to cover this up by claiming that everyone in town was just ignorant and/or in denial.
Sunnydale also seems to grow substantially in the first three seasons. In the first season several lines of dialogue make it sound like a small-ish town. Several people comment on how there's nothing to do or see there and Buffy is able to walk everywhere in town she needs to go. Later on Sunnydale is large enough to have its own University campus and a booming downtown district.
The notion that vampires are Always Chaotic Evil was starting to be done away with possibly as early as season 5, but it doesn't really take off until the Season 8 comics. The bonus/supplementary issue following 25, Tales of the Vampire, involves the aftermath of a teenage boy being transformed into a vampire, and neither he nor his vampire friends even come close to acting like any of the soulless monsters in seasons 1-3 of the television series. He briefly considers killing his mom, but quickly decides against it when she reveals that she still loves him no matter what. The idea of vampires killing people for food is even thrown out the window with Harmony's in-universe television show demonstrating that they can survive on non-lethal amount of blood from people. It goes hand in hand with the increasingly Black and Grey Morality of the series.
Smallville: The most egregious example of this was a vital clue hidden in a stained-glass window that hadn't been there in the previous episode, as well as the same window had been destroyed several times over the course of the series. The ridiculousness of retconning a window a week after it had last been seen casts a shadow on what would have been otherwise well-written.
The original meteor shower that brought Clark to Earth now includes Davis 'Doomsday' Bloom several feet away. Lionel's agents manage to reach Davis after the Kents have already carried Clark home.
The show introduced a major character from the comics, Jimmy Olsen, in S6. He had a supporting role for the next three years, then they decided to kill him off in the season finale. To keep the show in line with the comics, they had his funeral reveal that his name is actually Henry James Olsen, and it was implied that his previously unheard of little brother was the real Jimmy Olsen. Three years' worth of retcon!
In Friends, Ross is shown in later episodes as having a long standing passion for dinosaurs, that stretches back to childhood. However, in the first season, he states he only picked paleontology as his major on a dare.
Friends did this more and more with each flashback, resulting in the internal history making little sense. In the first episode, Rachel backs out of her wedding and we find out she hasn't seen Monica or Ross in a very long time. None of the other characters recognize her, but importantly, Chandler doesn't. But in Season 3, we find out that Chandler actually met Rachel just a year before her wedding day, and actually wanted to sleep with her. We then later find out that they met even earlier than that when Rachel was still in High School. This means that when Rachel met Chandler briefly in the Season 3 flashback, she didn't recognize him, or she didn't want her friends to know she knew him. Even worse, yet another flashback episode ("The One Where the Stripper Cries") would reveal that Chandler and Rachel actually hooked up during a college party.
An early episode also had a statement by Rachel that seemed to imply she met Chandler at Phoebe's birthday party! Luckily, the phrasing is ambiguous enough that it could also mean she met Chandler in the first episode as was initially assumed.
Friends was notoriously bad at doing more harm than good with their retconning, as the episode The One Where Chandler Can't Cry goes to show. The entire premise of the episode was (in typical Friends fashion) exactly what it said on the tin. Only, Chandler was easily the most emotional of the boys, and had several earlier episodes revolving around this fact. He had the same thing happen with his sudden and crippling fear of dogs. The same episode that introduced Chandler's dog phobia also reveals that Ross hates ice cream... despite the fact that a past episode (The One After the Super Bowl) shows him just fine with eating it.
Also, in "The One With the Prom Video", it's clear that Chandler had never seen Fat Monica or pre-nose job Rachel, but in a later episode he was retconned into meeting them...and actually caused Monica to lose weight!
Then in 'The One With The Sharks' it's brought up that Phoebe has never been in a relationship that lasted longer than a month, or lived with a partner, both of which happened at previous points in the series. While the whole living with a guy issue can be brushed off due to the fact Phoebe broke up with him after one night of living together, another episode had a boyfriend of Phoebe's mentioning that they have been together over a month. Phoebe also once mentioned, nearer the end of the series, that she had never been married before. She technically had - she married a Canadian man who she thought was gay so he could get a green card.
In yet another late season episode, it's suggested (through a throwaway line) that Ross got drunk and slept with the cleaning lady as a teenager. Really puts his constant whining during the first two seasons about Carol being his first and, until the start of Season Two, only sexual partner in a new light, doesn't it?
The most painful, quickest retcon ever was in The 4400. One episode revolves around re-opening the 4400 center. Notably, police try to stop it and tell Shawn he can't heal anyone, because no one can use 4400 abilities, whether they were a 4400 or got it via promicin injection. The very next episode features someone saying "Maia is a 4400, she can legally use her ability". The show then kept on like that without even acknowledging that superhuman abilities were entirely banned in the first few episodes of its last season.
In the episode where Zat guns (a type of stun-gun) were introduced, they were shown to be capable of disintegrating people and things if they were shot three times. This was used once to get rid of dead bodies that the crew didn't want to have to leave on set, once to destroy a dead body so SG-1 wouldn't get noticed, and once to destroy evidence of SG-1's presence during a time-travel adventure, then dropped completely because it was silly and overpowered. Now zats only stun people, or kill them if shot enough times.
This is referenced in episode 100 "Wormhole X-treme!". On set for the show-within-the-show, someone suggests giving their stun gun a feature to dissolve dead bodies so they won't have to be there for the romantic scene that follows, but the idea is denounced as stupid.
Another under-noticed retcon is the fact that Hathor was able to turn humans into Jaffa, which is mentioned both times she appears but never again. Apparently the other Goa'uld forgot how to do it too?
Not to mention the show retconning a number of things from the original movie, despite the movie itself still being mostly canon:
Ra wasn't the last of his species. (The series suggests that the Abydonians were tricked by Ra to think he was the only one, to ensure their loyalty.)
The Goa'uld didn't look like Protoss with mouths. Within the series this is never explained, but in extended universe material it says that Ra's previous host was an Asgard, which does look somewhat like the alien shown in the movie. Apparently the Asgard can't make for healthy hosts.
Abydos isn't "on the other side of the known universe," but one of the closest planets to Earth, which is used to explain why other addresses didn't work until they readjusted the dialing software to account for stellar drift. (Non-canon explanations state that the technicians during the first Abydos mission were incorrect with their calculations for distance.)
A few names were changed: Jack O'Neil becomes Jack O'Neill (which is lampshaded by O'Neil's statement that there's another Colonel O'Neil with one L, and "he has no sense of humor"); his wife Sarah and son Tyler become his ex-wife Sara and his son Charlie; Daniel's wife Shau'ri becomes Sha're; and the fictional Creek Mountain complex becomes the real-life Cheyenne Mountain complex. Sha'uri became Sha're because Michael Shanks (the actor playing Daniel Jackson in the series) had trouble with the "au" diphthong.
One of the better retcons from the movie was the reason for Daniel Jackson's career nosedive. In the movie, he's laughed at for arguing, with evidence, that the pyramids are older than we know, simply because he didn't know who built them. The series changed this so that instead of one of his mocking audience suggesting aliens built them, it was Jackson himself which makes his getting laughed at perfectly understandable.
One of the more plot-significant retcons has to do with the fact that the symbols on each gate are now the same except for one (the symbol designating the gate's point of origin), so they don't have to spend half of every episode figuring out the return address like they did in the movie. All addresses are based on points in space derived from Earth constellations.
In order to fit the constraints of a TV series, they dropped the language issues that were such a big part of the plot of the movie, and now the Stargate acts like a Universal Translator for some reason. It does this for every language except Goa'uld, Asgard, Ancient, and Unas, apparently.
Mid third season of Stargate Atlantis shows the first shot of the interstellar gate bridge. The first episode of season four shows its completion. Watch carefully in this scene. At one point, we see Carter moving past a computer with a wire frame of a Stargate, notably looking like it has an iris on it. Fastforward to episode seventeen where an entirely brand new line is added into the "previously on" segment, where McKay claims there is actually no need for the midway gates to have irises at all. This change is made for no reason other than to have an episode where the Wraith board the midway station and destroy it. The fallout of this episode is that the I.O.A refuses to build another because they're afraid of the same tactic. The possibility of building another and just adding irises is convieniently never brought up, so it would appear this retcon was all for the sake of justifying the permanent removal of a quick way back to Earth from the series.
A cross-series Retcon occurred between Cheers and Frasier. In a late Cheers episode, Frasier remarks that his father is dead and was a scientist in life, two things that are clearly not true in Frasier - it was explained as being the result of Frasier and Martin's relationship being quite cold at the time.
In Night Court, Brent Spiner played a character named Bob Wheeler from West Virginia. After a number of people from that state complained it was later revealed he and his family had actually come from Yugoslavia.
The series long neural-clone subplot in Farscape hadn't actually been thought of when Harvey first appears in "Crackers Don't Matter". The writers needed to think of a way to have Scorpius appear more frequently without losing his menace in the process, so decided to have him pop up as an offkilter hallucination. It worked so well, they ran with it and started dropping hints something more was going on inside Crichton's noggin, before introducing Harvey proper later in the same season.
Car 54 Where Are You? broke continuity to suit the backstory of the episode probably more than any other sitcom.
Red Dwarf is full of retcons. Major examples include the number of the ship's original crew being raised from 169 to 1169 (and raised to 11169 in the books), Lister having his appendix removed twice and Lister's relationship with Kochanski being altered from simply someone Lister was interested in but never asked out to ex girlfriend.
Angel had one about halfway through season four when the gang find out that Big Bad Jasmine had engineered most of the major events that brought the gang together.
in-universe, Angel had the gang's memories retconned to edit out Connor and allow him a normal life. Eventually, the reality alteration does get exposed, however.
Highlanderis full of retcons between the films and the series. One huge example is Connor's fight with The Kurgan. The series retconned it to simply being a really big quickening from a normal battle rather than The Prize. Other retcons were about the immortals' physiology and abilities. Series immortals died temporarily when injured, unlike the film, where they just kept on going and could walk under water without drowning.
Mighty Morphin' Power Rangers has one when it came replacing Rangers. In season 2 when Jason, Trini, and Zack had to leave the team needed to acquire a special sword to transfer their powers to Rocky, Aisha, and Adam, but in the following season when Kimberly need to give her powers to Kat she was handed her power coin away.
Also the ages of the original Rangers where 16-17 this is evidenced by the fact that they drive cars. The original finale "Doomsday" would see the rangers battle and defeat Rita and give up their powers and go to Prom. However based on the popularity of the show Saban altered the episode to not be a finale and leave room for more story. The prom part was cut out and the Rangers were Ret Conned to being 14-15 in order to keep them around longer.
Spooks the main arc of Season 9 qualifies (it qualifies as other nasty tropes too) Lucas is actually Evil!Lucas...turns out he was " lying to himself" being the perfect spy : it all comes out of nowhere and makes NO SENSE whatsoever
Prison Break did this with alarming frequency, to the point that they actually resurrected a character whose DECAPITATED HEAD WAS SHOWN ONSCREEN. This was retconned as a female guard helping her escape before the assassin had a chance to behead her. Instead, the assassin chose to behead the guard and deliberately left the package in a dark place, so nobody would look at the features.
That '70s Show does this with with a very early character, Donna's younger sister Tina. She appears in just one scene of one episode (Season 1 Episode 5) and is never heard from again. She is mentioned just once afterward in Season 2 Episode 6, in a joking Lampshadeing at the end by a soap-style announcer: "And whatever happened to Midge's daughter Tina? [...] Confused? You won't be, after the next episode of That '70s Show!"
Supernatural's Trickster secretly being the Archangel Gabriel. At the time of his creation in the second season, angels weren't even planned to appear in the show -That decision was made during the third season, due to the Writer's Strike cutting the season short. Then in the fifth season they're revealed to have been the same being all along.
Incidentally, the fifth season was planned to be the last.
The cure for vampirism. In the earlier seasons it was explicitly stated that there was no cure, but season 6 introduced one anyway. They try to Handwave it by stating the Campbells were keeping it secret, but this is flimsy at best -Wouldn't the logical thing to do be to spread knowledge of the cure to as many hunters as possible, so that more victims of vampires could be saved?
Good Times: The 1976-1977 season finale saw Florida marry an elderly gentleman named Carl Dixon and the two moving to Arizona (to tend to Carl's frail health condition); this was done to explain Esther Rolle's departure from the cast. When she agreed to return at the beginning of the 1978-1979 season, one of her demands was — and it was granted — that no mention of Carl ever be made, not even why he was no longer in Florida's life. (Rolle, whose Florida character was a devout Christian, said she did not want her character associated with a hardcore atheist.) Although fans often speculated about Carl's departure (death, a particularly acrimonious divorce, etc.), no mention about the Carl-Florida relationship or its end was ever made.
The MTV Reality ShowThe Hills was a major offender when it came to this. During the pre-credits voiceovers, new dialogue and/or footage would be added to address what the episode's focus would be, even if it conflicted with events as they were seen in previous episodes. These included, but were not limited to, pleasant conversations between characters being reframed to look more antagonistic, characters describing events that never could have occurred within the timeframe of the show, extra dialogue being looped into conversations (said when the camera isn't on them) to change the focus of the plot, and deleted footage that showed characters doing activities that they were never seen to have done in the previous episode. This fed a lot of fan speculation as to whether or not the show was scripted.
Monk has had a couple involving Trudy's death. First, it's originally stated that Monk was there by Trudy's side as she died from the car bomb, but later episodes show he was across town. Additionally, Monk originally did not know that the reason she'd left that fateful day was to pick up medication for his brother Ambrose, and Ambrose personally blamed himself for her death as he felt that if she hadn't done so than maybe she'd still be alive. However, in Ambrose's first appearance, along with a flashback to the day of her death in the series finale, it is mentioned that Trudy is picking up Ambrose's medication.
Additionally, in one episode as part of a gang of Chinese criminals' plan to lead him to Monk, they attempt to trick him with fortune cookies. One of the fortunes states that he will receive money from an uncle, which Randy rebukes since he only has two aunts and no uncles whatsoever (it was actually referring to tax return money, the uncle in question being "Uncle Sam.") Two seasons later, another episode is kick-started with the death of Randy's uncle. Not only that, but Randy visited his farm several times as a kid.
Gossip Girl has done this with Chuck's parents so many times that it's hard to keep track of what is currently canon. In the pilot both his parents are alive. Then it turns out his mother died giving birth to him and his father has never forgiven him for it. Then it turns out his mother is actually alive after all. Then maybe Elizabeth Hurley is his real mom and his Uncle Jack is his real dad. After that there was no point in trying to keep track anymore.
Showrunner Josh Safran really, really, really wanted people to ship Dan and Blair like he does even though Blair and Chuck are the show's Super Couple and the reason most people tune in at all. So in season five he alluded that Dan has had feelings for Blair all along and that in season one he was the only one who went to her (previously never mentioned) essay contest to support her. Never mind the fact that Blair and Dan hated each other until mid season four. Or that the episode that takes place a week after the supposed essay contest has Dan wondering if it's worth dating Serena (the girl he had been in love with for ages) because he's not sure he likes what it says about her that she can stand to be friends with a person as awful as Blair. Most of the fandom refuses to acknowledge that the essay contest ever happened since it doesn't fit in at all with what was going on in season one.
Safran took it even further in his interviews where he retconned so much stuff you wonder if he ever actually watched the show himself. A particularly glaring example is when he claimed Blair was never friends with Nate or Chuck. Even though the close friendship between the three of them and Serena is one of the key elements of the show.
CSI NY had Mac stating in the first episode that he used to sit with his wife in the hospital like he was doing with the locked-in victim. Although it could mean Claire was sick before her death and got better, it's likely that they retconned how she died on 9/11, from being pulled out of the rubble injured and dying in the hospital to her body never being found.
A more minor one was Clare being retconned as a blonde, rather than a brunette like in the pictures Mac showed Reed in season 4. There are reasons for having a different actress-the writers not knowing they'd need an onscreen Claire for flashbacks and the woman in the pics possibly not being a professional actress-, but it appears the casting department still got a bit lazy.
Forever Knight did some retconning of the main characters' histories between the made-for-tv film and the actual television series. Nick was only about 200 years old in the film, with Janette being about 400. This means that much of their history was only conceived for the film. Kinda justified, though, since a film wouldn't have as much backstory and character development as a series would over its run.
Wizards of Waverly Place had the episode "Alex's Logo", where Mr. Laritate has mysteriously forgotten that Ms. Majorheely "texted in her resignation". This is due to actor David Henrie writing the episode, but that doesn't justify the error. The majority of fans have already shunned this episode from canon anyway, not without reason.
Mythology and Religion
The practice of religious syncretism — the merging of two or more religious traditions — generally results in this, with older myths, texts and stories getting their context changed to make them compatible.
Due to its inherient nature, professional wrestling is full of retcons. This is especially true for angles (storylines) that flop or otherwise fail to resonate with the audience. In the years before the word gained negative political connotations, the terms "abort" and "abortion" were used in carny language to reference a suddenly-ended failed angle.
The NWA retconned the Fabulous Moolah's first women's title run, so the WWF retconned all of Fabulous Moolah's title losses, for 26 years anyway.
The NWA and Ring Warriors retconned Kacee Carlisle's forced defense of the NWA women's championship into a her getting an inexplicable shot at La Rosa Negra's Battling Bombshells Championship.
TNA did an extended storyline where Sting turned heel after Hulk Hogan and Eric Bischoff came on board. Hogan was clearly acting as a face, while it was hinted Bischoff might be working behind his back. However, Sting was a heel and was attacking faces. He made some vague comments about people not understanding, but he was a heel. Lo and behold, Hogan & Bischoff cheat TNA president Dixie Carter out of controlling interest in the company. As a result, Hogan and Sting's heel/face alignments are retroactively reversed.
Edge and Christian were initially portrayed as brothers but were later referred to as childhood friends (which they were in Real Life—they were born within a few months of one another, and raised in the same Ontario town).
Kane's (kayfabe) marriage to Lita was retconned due to the whole Matt Hardy/Lita/Edge triangle storyline/debacle. However, it was later reversed because Matt's been released for several years and blackballed from the company.
Magic: The Gathering has "The Revision". In the early days, the novels and comics were done by different companies than the card game itself, but when Wizards of the Coast became a bigger company they wanted to publish their own books. Reading the 10 books and the pile of comics so far was apparently too much effort for them though, so they issued a statement that everything that had come before was still valid, unless new stories contradicted them, thus creating what fans call "prerevisionist" and "revisionist" continuity. Several books were actually published that replaced older comics.
In both Warhammer and Warhammer 40,000, whenever fluff from one Army Book/Codex contradicts that of another book, it's stated to be the work of propaganda. This is because until later on an army can probably expect to see an update to their book every 2-3 years, and several had not seen an update for up to a decade (Dark Eldar was most infamous for this prior to their update), so there are expected to be massive gaps in the lore that don't match up. This also allows the author of each book to play up the badassery of the unit's Bestiary entry without much complain about Gameplay and Story Segregation, as the Bestiary entry is suppose to play up their badassery even if it's not true.
Warhammer 40,000 has undergone quite a few of these through its four editions, including entire races being retconned out. Anyone younger than 20 remember the Squats? Didn't think so.
The official policy on the Squats now appears to be that the entire race was murderlised by one of the Tyranid Hive Fleets. The Tyranids are God's gift to retconners. "Hey, what happened to those guys?" "Eaten by Tyranids."
Similarily, the Fimirs of Warhammer. Originally created to be the "iconic monsters" of the Warhammer world, they are now remembered only by people who played Hero Quest early in the nineties. Their reproductive cycle revolved around capturing human slaves for brides, which probably made for some thorny conversations with the parents of younger gamers. The Tyranids probably got them too, somehow.
Retconning happens at a minor level when most new editions of the army books are released, introducing new units and troop types into armies whose backgrounds have never included them before. Often these newcomers will be woven into the history of the faction in question to make it seem like they've been there all along.
Or, as a direct rewrite, to fix continuity errors. For example, in his first appearance in the Warriors of Chaos book, the Dragon Ogre Shaggoth Kholek Suneater was supposed to have been imprisoned in a glacier 700 years before the present by Teclis, the greatest wizard of the modern era. Since Teclis was actually born several hundred years after this date, the new version has changed it to "the greatest High Elf Mages of the day".
In Exalted, the Sidereal Exalted (who are basically Fate Ninjas) have a panic button called Avoidance Kata. Its effect? Retcon the whole world so that they made a different choice several minutes ago and are anywhere but here. Word of God says they've been there for a long time, we just didn't notice them.
Holden Shearer: They're very rare, they live in the cracks of the setting and perform their feats in dark times people strive to forget. But they're not new, as the GS Ps are new; thus, 'they were always there.'
Unknown Armies gives us Entropomancers (chaos mages who get power from taking risks), who are based around re-writing history. Cliomancers, despite being history buffs, can only affect people's PERCEPTION of history, as well as their memories. Of course, this still counts as retcon.
The "Luck" advantage in GURPS can have the enhancement "Wishing" added to it which allows the person using it to retcon a recent mistake into whatever result they like.
The writers have also retconned the weights a melee weapons as including the sheath in order to bring them down to reasonable levels.
Wizards of the Coast wielded a + 5 Rethammer in the Fourth Edition Forgotten Realms. Virtually the entire elven pantheon was retconned into one or more existing (usually human-ish) gods, along with the vast majority of the other minor gods. The previous planet of Abeir-Toril was changed to two separate worlds. Also gone is the Blood War, a massive near-eternal war between the devils of the Nine Hells and the demons for the Abyss for ultimate badassery.
They do give a reason why there is no Blood War. Asmodeus, the lord of the Devils, became a god and took a third option, by kicking the Abyss out of the way so they don't have to fight it.
A relatively minor, but still noticeable one was made to the war between the Gods and the Primordials. Originally, the Gods defeated the Primordials and banished them to the Elemental Chaos. It was later "revealed" that a third party, the Primal Spirits, intervened and ordered a truce.
Mystra dies. Again. This is the fourth time it happens.
In the early days of the storyline collectible card game Legend of the Five Rings, a number of card typos brought about story retcons. The most consequential of these was an oni card misprinted with the name of the hero Hida Yakamo. This led to a story point about Yakamo selling the oni his name, heavily influencing his character development and in the end being explained as the general model for oni-human interaction in Rokugan.
An actual rule of the universe in Nobilis: if you cause a car to fall apart, reality will insert a history of mechanical failures to explain that.
In BattleTech, a key point of the setting was that all capacity to build BattleMechs was irrevocably destroyed, and that the noble houses were fighting over remaining spare part depots. This was to play up a Mad Max / Scavenger World setting. However, they soon realized that no factories = no new designs to be introduced in followup supplements. Therefore, FASA later said that there were still factories producing new 'Mechs, but that they were degraded and no longer working at full capacity, and that the bleeding-edge tech of the Star League was no longer in production.
In Saints Row 2 onward. The game (and itssuccessors) lets you be a female, unlike in the first, where the Boss can only be male. The devs have stated that, canonically, if the Boss is female in the last three games, then she was female in the first one too.
The first Kingdom Hearts defines the Heartless as "those without hearts": when a person succumbed to the darkness in their heart, the darkness consumed it entirely, leaving them with no heart, thus, a Heartless. However, starting in Final Mix, the explanation is reversed: the Heartless is the heart, and the empty shell of the body becomes a Nobody. Additional information introduced in subsequent games only serves to make the whole thing even more confusing.
The adventure Sora and friends had at Disney Castle in Kingdom Hearts II. Donald and Goofy wonder what Heartless are doing in the castle. Queen Minnie escorts Sora to a hidden chamber below the throne and talks about the Cornerstone of Light. Maleficent sort of appears to them. Due to her meddling with the past, she can barely be in the castle until Pete destroys it. Sora and friends go through a magic doorway to the world of Timeless River and prevent Present Pete from breaking it with the help of Past Pete. So now Maleficent and her forces can't enter the castle in the Present, right? WRONG!!! By Kingdom Hearts Re:coded and Kingdom Hearts Dream Drop Distance, this was COMPLETELY forgotten. We see her and Pete holding the queen hostage, threatening to harm her unless they give her Jiminy Cricket's Journal.
In the original game, Ansem, the leader of Hollow Bastion, was said to be a once-benevolent king who became obsessed with the study of darkness and was eventually consumed by it. In the second game, however, we discover that the person everyone thought was Ansem was actually his apprentice, Xehanort, who had deposed Ansem and stolen his name, and that the real Ansem remained a good guy (for the most part). Kingdom Hearts Dream Drop Distance makes it even MORE screwey! The first Xehanort we ever saw, "Ansem", went back in time and made his past self evil to start with, and the entire nature of Xehanort's past plans have changed as to be more interconnected, with his big plan involving creating thirteen versions of himself, through both time travel and infusing his heart into other peoples' hearts.
Also, due to legal issues, the events of Deep Jungle were retconed out of existence, resulting in the world and all it's inhabitents to disappear completely.
From the first game we are given: "You are the Master Chief, born for battle, bred for war, you are the last of Spartan-II project. Your brethren have died". The novel Halo: First Strike then reveals that a number of others survived. The games never reference any of this. Also, there was another Spartan right there on the ship, albeit in a cryopod due to her injuries. Even then, she was supposed to be dead. They changed that to clinically dead but resuscitated her through complex surgery.
Halo: Reach heavily retcons Eric Nylund's Halo: The Fall of Reach, which described the origins and early years of the SPARTAN-II program, as well as the Fall of Reach. In the novel, the Pillar of Autumn is already on its way out of the system when the Covenant attack on August 30, 2552. The ship turns back and the Spartans split up; the Master Chief leading a small team to destroy a ONI Prowler's NAV Computer (in accordance with the Cole Protocol, all vessels are to destroy their navigational databases upon contact with the Covenant, lest they discover the location of Earth.); the rest head to the surface to defend the generators powering the orbital MAC Cannons, the only thing keeping the Covenant from achieving victory. By the time the Chief completes his mission, the generators have fallen, a ground invasion is underway and the Covenant have control of orbit. Left with no alternative, the Chief heads back to the Autumn which flees the system. Rather than plotting a blind path (again, the Cole Protocol), Cortana uses data from a Forerunner crystal to plot a course to Halo. The first game's plot follows. Halo Reach, meanwhile, has the Covenant raiding the planet as early as July 24, and the rest of their fleet arriving on August 14. The Pillar of Autumn is in drydock on the surface, with the exact location of the Spartans uncertain (an Easter Egg already has the Master Chief in a cryopod). The final mission has Noble Team escort a fragment of Cortana to the Pillar of Autumn just as it escapes Reach. Cortana plots a course to Halo based not just on the Forerunner crystal, but with data gathered from Reach's own Forerunner artifact. Cue massive Fan Dumb/Fan Wank.
The earlier Halo novels stated that the Elites, Hunters, and Brutes were not encountered by humanity until the last year of the Human-Covenant war. This was contradicted by so many other sources that the 2010/2011 reprints of said novels retconned away any mention of them being newly encountered species.
Albert Wesker in the original Resident Evil was a stock horror film character, the obligatory traitor who gets killed at the end. Realizing that the series was in need of a main villain, they brought back Wesker from the dead in Resident Evil: Code: Veronica and released a fictional documentary called Wesker's Report which explained that Wesker was behind the events of Resident Evil 2 and Resident Evil 3: Nemesis as well.
In the original PlayStation version of Resident Evil, the severed hand founded by Joseph Frost at the beginning of the game was originally established to be that of Edward Dewey's, Bravo Team's originally unseen pilot. When both, the remake and Zero came out, Edward Dewey was established to had died earlier during the events of Zero and the corpse found by Joseph now belongs to Kevin Dooley, a helicopter pilot who accompanied Bravo Team on their mission.
Originally, the team wielded generic Beretta handguns in the PlayStation version of the first game. Resident Evil 3: Nemesis then introduced the Samurai Edge, a customized Beretta that was planned to be adopted as the standard-issue sidearm by S.T.A.R.S. before they disbanded. In the GameCube version, the S.T.A.R.S. members now use the Samurai Edge.
Resident Evil 2 has Annette Birkin, a paranoid wife of the now mutated monster, William Birkin. She is continues her husband's legacy of the G-Virus research and is angry at Claire for "killing" her husband. However, Resident Evil: The Darkside Chronicles rewrites Annette's character to be more sympathetic and is willing to stop her husband after he mutates.
Lisa Trevor was added to the rewritten canon of Resident Evil 1. A child savagely experimented on but instead of dying from the viruses, she absorbed them becoming almost invincible. Eventually turning into a mindless hulking monster that stalks the Arkay Mansion.
StarCraft Brood War: In the original game, the Terrans are portrayed as a near-offshoot of humanity long isolated from Earth, with a separate historical and technological development. The swift arrival of a United Earth Directorate with similar technology and language in the Expansion Pack manages to contradict the spirit of this several times over. The first U E D mission is partially about stealing Terran technology, a mention is made of the configuration of the U E D flagship being unlike any Terran ship yet encountered (despite looking identical), and the manual tries to Handwave it away with references to bugs built into Terran equipment (and the U E D is the in-game explanation for several new units and technologies) but even a rather lenient interpretation of events has trouble making it all fit together.
StarCraft II had a pretty big one involving the Zerg Overmind. In the original game, the instruction manual states that the Overmind was created with an imperative to absorb creatures into the Swarm and thereby improve the Zerg. This is what caused it to rebel and overrun the Xel'Naga. SC 2 states that another force interfered with the creation of the Overmind, enslaving it to that imperative. It also says that the creation of Infested Kerrigan and the death of the Overmind was all part of a Thanatos Gambit to free the Zerg from this control. Kerrigan wouldn't have his imperative. So after creating her, he then went to the most powerful species in the sector, set up camp on the homeworld, and gave them both a reason and the opportunity to kill him. This also conveniently explains why in SC1, the Overmind decided to leave the all-important Kerrigan behind when he went to Auir.
Before Starcraft II even began, you had the retcon of Blizzard deciding to make the Brood War Praetor, Artanis, the Player Character from the Protoss campaign of the original Starcraft. It doesn't seem to have effected much, but it does make a lot of Brood War's dialogue with anything containing Artanis odd. Most characters, especally Aldaris, treats Artanis like the new guy that knows nothing, even though he's now supposed to be the war-experienced Executor from the original game's Episode 3.
Kerrigan now has split-personalities in Starcraft II instead of being the lone queen-$&%@#-of-the-universe from the original games. It's clear Blizzard wanted to return Kerrigan to the good side, and wanted the whole Raynor x Kerrigan romance to happen, but to do it, they would have had to have Kerrigan accomplish something extremely redeeming for her. Only Blizzard didn't decide to go that route. They copped out and made it so that her BAD side was what caused all the destruction while the GOOD side is inside the Queen of Blades somewhere struggling to get out. Not once in either of the original Starcraft games is there ever a hint of Kerrigan possibly having split personalities. This plotline was only added in Starcraft II to get Kerrigan back on the good side in the least amount of believable work as possibe.
Tassadar isn't completely dead anymore. He's now an all-knowing ghost that hangs out around the rotting carcass of the Overmind.
Zeratul is bewildered and questions who could've created such an abomination when he omes across a living Hybrid...this comes many years AFTER meeting Duran in Dark Origins and learning of the his Hybrid experiments.
Rivaling the Klingons are the orcs from Blizzard'sWarcraft franchise. In the first two games the orcs were simply Always Chaotic Evil, but in the third game they were now led by Thrall, a young Shaman, who wants to return his people back to the way they were before the Burning Legion came to Draenor. It turns out that, instead of being bloodthirsty idiots for 100 years as originally stated, they were a peaceful race of warriors who had been corrupted by the Burning Legion only about 5 years before they came to Azeroth. This meant that several orcs remember the time before the corruption. To help with the retcon Blizzard has made a book explaining the corruption and has planned two new books that will show what really happened during the Tides of Darkness and Beyond the Dark Portal video games.
To Blizzard's credit, though, they have admitted that gameplay and balance FAR supersede continuity in the context of how important they are, and that if they can't make a game element fit within the confines of the established lore, they WILL alter it to suit their needs. Adding in a dash of Unreliable Narrator (given that all of the tie-in-books and game-based-lore are, in some form, intended to have been documented by those present for those given events) also helps explain inconsistencies, using a Watsonian explanation for certain elements.
Blizzard stated in 2013 that the Warcraft movie is intended to tell the "true" events of the early games, indicating yet another retcon.
Even when one allows for fanon, it's often argued that the draenei are an even bigger retcon than the orcs. In the first two games, they were presumed to be an extinct race. But some survivors (ugly raptor-footed mooks) appeared in the third game. Then, when the Alliance needed a new race in World of Warcraft, the draenei were picked...and their appearance was changed to make them look like smaller, bluer eredar (big demons who had been heavily involved in the corruption of a titan and were the main villains of the third game). The explanation was that the eredar from the third game are actually the man'ari eredar, a corrupted form of the original Eredar, who were actually the draenei. No one's quite sure what corrupted the titan in the first place (dreadlords were definitely involved, but it seems unlikely that it was them alone), but he was the one who corrupted the eredar, rather than the other way around. The draenei in the third game were revealed to have been mutated by demonic magic. In other words, the draenei the players play are the original unmutated draenei, who are in fact the original uncorrupted eredar. Does your head hurt yet?
Let's not forget their Horde counterpart, the Blood Elves. Supposedly they all followed Kael'Thas into the Outlands, but in World of Warcraft, there are a lot of them left in Azeroth, and not only that, they also managed to rebuild half of their capital city in a mere four years. And seeing as there are two banks and auction houses in it, business is obviously going great.
That one was actually covered in expanded universe material to an extent; the rpg books that came out shortly after WC 3 explained, in a fairly minor retcon, that while most of the elves in Quel'Thalas and Silvermoon were slain, the city itself was largely left in tact. The main problem was that it was still invested not only with zombies, but with the ghosts of the citizens slain there. The rpg also mentions some blood elves coming back to Azeroth prior to TBC, though not as many as depicted in World of Warcraft.
Though the RPG also introduced even more retcons into the Blood Elves' backstory, by having them be a minority of the high elves rather than all of them, having drained demons before meeting Illidan, having night elves attack them on sight and having them be nomadic.
Also see Not Quite Dead and Staying Alive for mind-boggling character revivals in the game universe. Blizzard heavily retcons everything to make new quests (the Black and Blue Dragons were originally stated to have only the aspects left), and make some playable units (see blood elves and draenei). The fans have just learned to accept it.
A rather nasty example comes from the plotline regarding Arthas in Wrath of the Lich King. A plot twist occurs in the Icecrown Citadel instances stating that killing Arthas would only enrage the undead and make them more destructive because it's actually only Arthas' will that are holding them back. However, this seemingly contradicts earlier quest chains which establish that Arthas has no humanity left due to ripping out his own heart and having it manifest as Matthias Lehner. It also causes even more problems when you consider the fact that there's no real reason given why the undead would become more mindless and destructive given that we've already re-killed most of them and we have seen how the Forsaken have free will and aren't mindless at all. They might be bitter and angry, but not mindlessly destructive. It all seems like a thinly veiled excuse to give a reason why the undead and the Lich King are still around after Arthas dies.
Word of God said that it is not that if there's no Lich King in charge of the Scourge, Yogg-Saron would take over, power them up with Lovecraftian eldritch powers or whatever, and have them kill everything as was implied. Rather, for unknown reasons, Arthas and Ner'zhul held the Scourge back.
Worgen: Barely sentient ravening extradimensional hellhounds, or just druidic devotees of the wolf god who lost control?
A main one, and one everyone seems to forget is that Deathwing, the Big Bad in Cataclysm was killed in the canon campaign of Beyond the Dark Portal in Warcraft 2. Handwaved by Blizzard that he faked his death by crashing into the ocean.
The Imperial Province (Cyrodiil) was always described as being covered in a thick jungle (ref: Pocket Guide to the Empire and numerous in-game books and NPC accounts). In The Elder Scrolls IV: Oblivion, the first game to take place there, the jungle has turned into generic fantasy forests and meadows. The explanation for this: A god made the land colder for some soldiers who were too hot and the jungle vanished.
The first 2 games, as well as the spinoff Battlespire, mention that there is no race native from the Imperial Province, that the province is a cosmopolitan mish-mash of all the other races. The Imperial line is supposed to be Nords. Then comes Morrowind, introducing the Imperial race, and retconning them as a descendant of the original Nord caucasian race, from which the modern Nords, Bretons (via mix with elves) and imperials are all descended from. The retcon does maintain that the Emperor's family has more Nord blood then most Imperials.
One could say that most of the convoluted lore concerning the Elder Scrolls universe is the result of a massive retcon to make all of the possible endings of Daggerfall canon. At the same time.
The Elder Scrolls Online has drawn the ire of lore-minded fans due to its developers' in-universe explanation for depicting Cyrodiil as forests and meadows again. As TESO is set a good 800 years before the main series begins, the explanation used in Oblivion wouldn't work, so they explained away the tropical rainforests by calling said depiction a "transcription error."
Final Fantasy VII has the "Compilation" cheerfully retconning quite a good deal of the original game's backstory, to the consternation of many fans and the relief of others. For a sample of the changes, take a deeeeeep breath: Crisis Core retcons bit-part Zack into a lovable hero, Aerith was likely in love with him before Cloud (in the original game, when Cloud asked if Zack and Aerith were "serious", Aerith replied, "No... but I liked him for a while") and received all much of her trademarks from him, Genesis orchestrated the Nibelheim incident (though it seems to have gotten far more out of hand than he intended), and Zack died fighting what looks like the entire Shinra army before passing on his memories to Cloud (a heroic passing-of-the-torch instead of an epic Mind Screw). Before Crisis forever cements the Turks as wisecracking antiheroes instead of villains, portrayed similarly in CC and AC, but on a larger scale with many members here, as well as adds a different incarnation of AVALANCHE that existed before Barrett founded his group, making them behind many events that occured prior to the original game; Advent Children itself changes the personalities of many characters, but especially Cloud (considerably more mopey) and Vincent (considerably less mopey); and Dirge of Cerberus retconned considerable amounts of Vincent's backstory, making HIM more mopey, and added an entire army of subterranean Super Soldiers to the canon where there were none before).
Cloud being considerably more mopey in Advent Children is explained in a blink-and-you'll-miss-it-moment: The Geostigma that infects people doesn't just hurt them, it also fills them with doubt and angst and other bad emotions. Naturally, Cloud is able to resist it long enough to maintain his Badass-edness, but it isn't until his stigma is cured that he actually stops being mopey and truly becomes his Badass Super Soldier self.
Interestingly, some of the retcon in the compilation has already been hit by the Reset Button, as aspects of the Nibelheim Incident changed in the anime short Last Order were retconned in Crisis Core to be more similar to the original game's events.
Word of God has stepped in to say that all depictions of the Nibelheim incident represent a different character's perspective and memory of it; bits and pieces of each recollection collectively form what truly happened.
Sonic the Hedgehog's retcons are confusing at best. Shadow's dead, no he's not, he's alive, except he's a robot (revealed in the same game where's he found to be alive), except he's not a robot, he's a clone, except he's not, he's really the original Shadow. A retcon so bad it took twogames to sort it out.
Then there's the entire re-imagining that everything post-Sonic Adventure has brought, with some characters gaining a year, some characters becoming four years older and and one losing ten years. One only has to look at the Archie Comics version of Sonic to see how much of an effect this has had on the early stories.
To officially summarize the Shadow Retcon: Shadow was nearly killed in his heroic sacrifice, but Eggman recovered his body, only to be surprised that he was alive! However, Shadow was amnesiac. Eggman, figuring that there's no reason not to use this, promptly made some clones/robots, and then began screwing with Shadow a little to manipulate him.
Sonic Adventure retconned the Master Emerald's location. Instead of the underground Hidden Palace Zone, it now rests in a much smaller, outdoor temple.
Team Fortress 2 has had a few retcons since the developers have tried to add more back story to an otherwise plotless game as well as shift the tone from lighthearted mid-20th-century pulp to full-on wacky comedy.
The back story of the Demoman originally told of him killing his biological parents while trying to blow Nessie out of the water, then growing up in a foster home afterward. However, when a comic from the WAR! update in December 2009 depicted the Demoman talking to his real mother (who, in turn, talked about his real father), Valve retconned this by saying that he had only killed his adoptive parents, and his biological parents later heard of his great skills at explosives and took him out of the foster home for proper training.
And now, the Demoman's eye story gets changed yet again, this time his eye was possessed by MONOCULUS! in the Bombinomicon (Halloween 2011) comic. It isn't known if it's the same Demoman, or if the RED and BLU ones have different back stories with the same result.
RED and BLU were originally described as "two holding companies that secretly control every government on earth." Since then, it has been revealed that they're actually the end product of a petty squabble between two rich but dimwitted brothers who inherited half of their father's useless real estate each and are in the process of squandering their liquid assets fighting to gain control over the rest of it, with the delusion that it will help them corner the market on gravel. All the businesses they supposedly own were merely fronts for more fighting, and nobody has ever been fooled by them.
The Street Fighter series had its fair share of retcons, but some of them are not actual legitimate changes to the story so much as they are actually the result of inconsistent translations between the Japanese and English versions of the game (such as the revelation in Super SF II that Cammy was M. Bison's lover in the past, which never actually occurred in the Japanese ending). One legitimate retcon concerns the many ways Guile's combat buddy Charlie has been killed off throughout Alpha series (stabbed in the back in the first Alpha, gunned down in Alpha 2, and died in an explosion in Guile's ending in Alpha 3). The early anime trailers for the console version of Street Fighter IV implied that Charlie may not be dead after all, but Guile's prologue and ending in Super Street Fighter IV seems to suggest that Charlie is dead again.
The biggest retcon, however, is saved for Gouken, the original master who trained Ryu and Ken. While Gouken's origins, identity, and even existence remained ambiguous for much of the franchise's early years, slowly the character began to emerge and was portrayed as the long-dead (and inherently mystical and mysterious) master killed by his brother, Akuma. Then suddenly in Street Fighter IV, the character's back story was blatantly Retconned to add in the convenient fact that Gouken was never killed, just rendered in a coma and everyone (Ryu, Ken, Akuma, etc.) thought he'd been dead all this time. Admittedly, Gouken was included in the game almost solely as a nod toward the infamous Sheng Long "secret" but nonexistent character in the Street Fighter series, as well as rumors throughout several games that Gouken was somehow playable. Still, this massive Retcon removed most all of Gouken's mysterious, mystical nature and turned him into a standard, more generic fighter.
Bison was officially considered dead following Super Street Fighter II: Turbo and remained that way until Street Fighter IV. Now he apparently has multiple bodies stored somewhere in case his soul needs to inhabit a new one. Never mind that he was supposed to have been killed by Akuma's Shun Goku Satsu, which sends the victim's soul to hell where it is attacked by demons.
Myst series: First, Revelation changed the entire concept of trap books by turning them into prison ages instead and having Sirrus and Achenar return. It also introduced Yeesha, who later on in Uru and even End of Ages bent so many of the rules of Writing Ages that she practically threw both canon and fanon out the window. At least Uru acknowledged that what Yeesha could do was out of the ordinary ("I could write things they never thought possible"). Myst IV on the other hand seemed to act as if the prison books had always been that way which just doesn't make sense. In fact, Uru (and later Myst V) attempted to explain away all the "inconsistencies" of the first four games in a rather interesting way — they are, by Uru canon, JUST VIDEO GAMES. Yeah, it makes sense, but still seems like a slap in the face to some fans of the first (and arguably best) games.
The Metroidremake, Zero Mission, contains a great many retcons to the original story, most along the lines of what happens to Samus after she defeats Mother Brain. However, things such as Kraid and Ridley getting massive growth spurts (to match their portrayals in later games) are clearly Re Write territory.
In Metroid Prime, there was a Chozo barrier around the Impact Crater, which stopped the Space Pirates from getting inside, where Metroid Prime (the creature) was. However, in the first US version of the game, Pirate logs indicate that they captured and studies the creature before it escaped. This was very quickly retconned when they realised it was impossible - in the normal English version and the Player's Choice versions of the games, the Pirate logs only say that they know there is a creature there, but they don't know what it is. But even in the non-US versions, the scan data of Metroid Prime says it has mechanical weapons, which (in the US version) it assimilated when the Space Pirates were experimenting on it. Either way, it's still a Plot Hole.
Metroid: Other M has some scenes that people have cited as being rather continuum breaking.
The biggest one seems to be the infamous PTSD scene where Ridley appears in front of Samus, which makes the heroine scared stiff while we briefly see her as a little girl just as scared of him before he begins carrying her to her would be death. The scene is actually lifting a plot point from a then non-canon manga which mentioned that Samus' parents were killed by Ridley. Because this plot point was not introduced until the manga, and because the manga was not released until after the release of Zero Mission, we're left to wonder why Ridley's presence never did this to Samus to begin with, and why after numerous encounters with him, is she still scared of him.
The mechanic of Samus not using any of her weapons or skills until Adam approves of it annoyed many players, especially when she doesn't activate her Varia Suit in an area of the Bottle Ship that has an extreme temperature risk. Although it was only a way for Nintendo to explain off her not being able to access the power (and for Nintendo to prevent people from sequence breaking the game, something that they have been trying to curtail since they saw how extreme people got with Super Metroid), it was odd that Samus was only now deciding to obey someone. This and many other issues with the story were actually brought up in the next game of the chronological order, Metroid Fusion: The AI actually brings up Samus' willingness to follow Adam's orders to the letter, even if it means certain death for her, as if the AI was puzzled at how obedient she was to him.
Then there's the whole thing with Adam apparently being "the only father figure [Samus] had ever known," seemingly retconning Samus' entire Happily Adopted relationship with the aliens who raised her.
In Summoner, Laharah is an evil goddess, and her followers, the Nuvasarim, feed on agony. This is thoroughly - and convincingly - retconned in the sequel, in which Laharah is the protagonist. except that neither Laharah, nor Urath, nor any other gods exist. They are all merely parts of Aosi. What's that you say? Vadagar's giant three-headed corpse? We didn't walk through any giant three-headed corpse!
Dark Reign has an ingenious version of this: the first twelve missions are recreations of famous battles between the Freedom Guard and the Imperium. You choose which site to fight for, but the historical results of the battle will not necessarily match your victory. The final mission involves going back in time and retconning history itself by saving Togra and defeating both sides. Thus, the retcon is part of the plot.
In Backyard Skateboarding, the playable characters have allegedly never heard of several neighborhood kids. This would fit in continuity for Andy MacDonald, but not for the Backyard Kids because they played in the same league as them for a few years! In MANY different sports! (It may be that Skateboarding is supposed to be from Andy MacDonald's perspective, with the others as just playable.)
Metal Gear Solid 3: Snake Eater made a few changes to Big Boss' initially established back-story from previous games. Originally, Big Boss was stated to be born around the 1920's , meaning that he was in his 50's when Solid Snake was born during the 1970's and over 70 when Solid Snake (supposedly) killed him in Metal Gear 2, which was set in 1999. However, he's only 29 in Metal Gear Solid 3, which is set in 1964, meaning that he was de-aged by roughly ten years. Likewise, Big Boss' bio in the Metal Gear 2 manual stated Big Boss lost his eye during the 1980's, a few decades later from the events of Metal Gear Solid 3 (where Big Boss loses said eye during an interrogation session).
Liquid: The price of physical prodigy... Few more years and you’ll be another dead clone of the old man. Our raw materials are vintage, brother. Big Boss was in his late fifties when they created his copies.
The eponymous walking nuclear tank itself has had its history changed as well. The TX-55 Metal Gear from the first MSX game in the series was originally the first of its kind, until RAXA and the ICBMG (both from MPO) , as well as Metal Gear Zeke from Metal Gear Solid: Peace Walker, revealed that there were at least three models before it (technically four, if one counts the eponymous weapon in Peace Walker as a Metal Gear).
Gray Fox's back-story was also heavily retconned in MPO. In MG2, Gray Fox reveals during his death scene that he was a half-white war orphan from Vietnam who was adopted by Big Boss after the war was over (which would have been after 1975) and later served Renamo (the Mozambican National Resistance) during the Mozambican Civil War. In MPO, we find out he was a German-speaking child soldier from Mozambique who fought for the Frelimo (who were the enemies of the real life Renamo) in 1966 (four years before MPO and nine years before the Vietnam War ended). The Metal Gear Solid 4 Database doesn't even mention Gray Fox's time in Vietnam, nor his time serving Renamo.
The identities of the Patriots have been changed multiple times since the first mention of the organization. In MGS2 they were suggested to be both an Illuminati-like secret council composed mainly of twelve members known as the Wisemen's Committee. The timeline in the ending of MGS3 stated that the Patriots were actually the US branch of the Philosophers, which was the real Illuminati-like organization. But then MGS4 established that was really a cover for their true origins (MPO having previously revealed that the US Philosophers were murdered by Ocelot under orders from Zero) as a different group founded by Big Boss and his team from MGS3 as a sort of continuation of the Philosophers, which Big Boss left over a dispute with Zero, and which Zero passed on to a group of AIs; and that furthermore, Donald Anderson from MGS1 was really Sigint, and Dr. Clark (who revived Gray Fox as a cyborg) was Para-Medic, and that their "accidental" deaths (Anderson's from being tortured by Ocelot, Clark's from Fox's rampage) had been orchestrated by Eva and Ocelot from the get-go as part of their plan to destroy the Patriots and rescue Big Boss. And the really weird thing is, after playing all the games all of the above will make perfect sense.
Peace Walker retcons both, Snake Eater and Portable Ops, by revealing that the DCI was not the true mastermind behind The Boss' death, who was actually following orders from Hot Coldman, the true culprit.
A lot of the plotpoints from Metal Gear 2: Solid Snake were retconned as early as Metal Gear Solid. For instance, Metal Gear 2: Solid Snake heavily implies in both its intro and the instruction manual that the entire world was actually disarming its nukes and the only intact nukes were procured by Zanzibar Land by raiding nuclear outposts. However, Metal Gear Solid retcons this by exposing that more than 20,000 nukes still exist in the world either by 1998 or 2003, despite their goal being to get rid of them by 2001 or 2007, as well as the fact that they were creating nukes, and that START II, which was stated to have not only been ratified, but also implemented long before the events of Metal Gear 2, was mentioned to have not even been ratified yet by the time of Metal Gear Solid. There's also the infamous implication of Big Boss stating that he is Snake's father in Zanzibar Land.
In Silent Hill, the exact nature of Silent Hill changes dramatically between games, comics and the film. Silent Hill 1, Origins and the film imply, or outright show that the fog-world and otherworld are caused by Alessa, in retribution for the crimes committed against her. This changes in Silent Hill 2, and is featured in some the comics, which suggests that the town was always a dark place, and that Alessa just caused the evil it to break through into our world. It switches again in Silent Hill 3 and Homecoming, both feature the fog world being caused by the Order, and that they are able to control it to some degree. Other comics say it was caused by the impregnation of a woman by Whately, who does not appear or is mentioned in any of the games. Finally, Silent Hill Downpour suggests that the town itself is sentient.
The first few .hack// games avoided this by being a direct sequel to the anime .hack//SIGN; on the other hand, Roots contradict various aspects of the G.U. games (both were released about the same time, but when Roots reenacted some of G.U.'s scenes, the first game was already available for months). The most jarring ones:
Shino's death scene (in this case, the retcon was caused by the games). While the scene is essentially the same in both versions, some minor details were changed to contribute to the drama of Alkaid's death scene in the games. Shino got lines when in the anime she didn't say anything, among other changes (such as Haseo not calling her on her phone). Shino's outfit coloring also suffered, as in some of the game's flashbacks it would be black (that is, post-Ovan-disappearance) when, according to the plot, it should be white.
Champions Online seems to be lampooning the trope: "Retcon" was their custom term for a respec, until some players got confused by it!
Some (minor and easily Handwaved details from the first Jak and Daxter game don't exactly mesh with revelations made in the later games.
In the Ace Attorney series, it was rumoured amongst characters in the original first game that Edgeworth was so hellbent on always getting a guilty verdict that he sometimes faked evidence. However, according to case added in the DS remake, Edgeworth never faked any evidence, and it was all a nasty rumour. Some fans did not take kindly to this, claiming it rendered a good portion of Edgeworth's Character Development in the first game moot.
In Pokémon Red and Blue and Yellow, as well as FireRed and LeafGreen, Giovanni vowed to make amends for his actions, feeling he betrayed his followers and renouncing Team Rocket for good. However, an event in HeartGold and SoulSilver reveals that Giovanni had in fact planned for Team Rocket to be revived, that he wasn't truly remorseful for betraying them, and the only reason he left was to get stronger.
Also, in Gold and Silver, Steel- and Dark-types were stated to be new types. This was omitted in the remakes, owing to the fact that the previous games, even Fire Red and Leaf Green, also had Steel- and Dark-types.
Essentially, players should treat FireRed/LeafGreen and HeartGold/SoulSilver as the "true" versions of RBY and Gold/Silver, respectively.
Also, Steel was retroactively added to Magnemite and Magneton, which were pure Electric-types in the first generation, completely changing their type matchups. Similarly, Pokémon X and Y added the Fairy type, which was also retconned onto a number of older Pokémon, with a few (specifically, the Clefairy, Togepi, and Snubbull families) actually losing their former Normal types entirely.
Both times new types were added, other types gained and lost weaknesses unrelated to the new types as well, such as Steel losing its resistances to Dark and Ghost in the sixth gen when Fairy was introduced.
Some of the breeding mechanics amounted to retcons as well. Several species that once only bred more of their own kind were explained to not have been able to produce their pre-evolutions earlier due to not having the proper held incense. The families of Wobbuffet, Mr.Mime, Azumarill, Chingling, Snorlax, Mantine, Sudowoodo, Roserade, and Blissey are all part of this. They'll produce the middle or highest member of their line, depending on the species, when bred without the proper incense, and the baby member of the line only when bred while holding said incense.
Kyurem in Pokémon Black and White was catchable in the post-game. But the sequels seem to have retconned that it was not caught by the previous player character and was instead captured by Team Plasma.
They also retconned in some evolution methods; while most evolutions of older Pokémon use either a game mechanic or an item that wasn't available in previous games, Pokémon Diamond and Pearl gave Lickitung the ability to evolve if it's leveled up with Rollout in its moveset, and Yanma and Piloswine gained similar evolutions with AncientPower. However, Lickitung could learn the move via TM in the second generation or tutor in the third, and you can breed AncientPower onto a Piloswine in any generation.
Herman Toothrot is a loony eccentric in the first two Monkey Island games. In subsequent games he is inexplicably identified as the grandfather of Guybrush's love interest Elaine Marley. This contradicts a large chunk of the established story, and much shoehorning has to be made.
The Legacy of Kain series pulls an interesting in-game example: at the end of Soul Reaver 2, when Kain changes the timeline by pulling the Reaver out of Raziel, the timeline itself retcons Blood Omen 2 and parts of Defiance into existence to prevent time from being destroyed.
Guile, a character that the player can recruit in Chrono Cross, was actually meant to be Magus from the previous game. The developers said that they eliminated his backstory because of time constraints and because they didn't want any of the "secondary" characters to have more importance than the others, but evidence still exists that the two were originally meant to be the same person (they both hover instead of walking, have long white hair, and use Shadow magic; Guile's Japanese name, Alfador, is the same name that the child Magus gave to his cat in Chrono Trigger). Surprisingly, in the Updated Re-release of Chrono Trigger for the Nintendo DS, they retconned the whole story by having Magus lose all of his memories in a canonical ending, thus strongly implying that Guile is an amnesiac Magus.
The same thing can be said about Dalton. In Chrono Trigger he was a joke villain, but in one of the bonus dungeons of the DS version you can fight him and discover that he's planning to raise a huge army in Porre and destroy Guardia (Crono, Marle and Lucca's hometown). Of course, Chrono Cross tells us that Guardia has indeed fallen against Porre's army.
Left 4 Dead went through this a few times. During the development of the game, each campaign was supposed to continue in sequence in the storyline, but play testers complained that they felt it was too much of a downer to see the survivors get rescued and wind up having it fail, starting the next campaign. Valve then made it where each campaign is a separate story. Fans then started to complain that the campaigns felt too out of place, so Valve made the Crash Course campaign that tied in between No Mercy and Death Toll. Possibly due to Fan Wank, Valve made the sequel have the campaigns be all connected in sequence and it was met with positive reaction. In response to this, The Sacrifice comic goes to state that the survivors from the first game have, in fact, gone through several rescues in each campaign one by one (No Mercy, Death Toll, Dead Air, and then Blood Harvest).
Raiden's story in the first Mortal Kombat title was much more self-serving, as he had been invited by Shang Tsung to compete and does so in order to prove mortals are puny when matched with a god. His ending from that game has him overthrow the tournament and turn it into a showcase of the gods (that eventually destroy the world). Later games throw this characterization out the window and instead portray him as a concerned protector who feels he must participate in order to avert disaster (as this happens after the first movie also changed the entire story of the first game).
Kabal from Mortal Kombat 3 was given the same treatment. The third game presented him as a reformed gangster seeking revenge for the deaths of his comrades and his ending states that he devotes himself to fighting injustice. Fast-forward to Mortal Kombat Deception, and not only has Kabal returned to his criminal lifestyle, but he's one of the antagonists in the game.
The sixth route of Duel Savior Destiny hastily claims at the end that Mia is Not Blood Related to Taiga as a saving throw to prevent 'real' incest. The final route, however, establishes firmly that they do have blood ties.
The Koopalings from Super Mario Bros. were originally introduced as Bowser's children. However, after this game this was not mentioned again, and the Koopalings got called Bowser's "minions" in later games, but the "Bowser's children" wasn't disproved either, leading fans to still believe they were his kids. It was not until a 2012 interview that Miyamoto officially said that "in the current story, the Koopalings are not Bowser's children."
In Mass Effect 1, Saren's hatred for humans was said to be the result of his brother Desolus getting killed during the First Contact War. This was contradicted by the later comic miniseries Evolution, in which it's revealed that Saren himself killed Desolus, because his brother was a General Ripper who intended to turn the entire turian population into monsters in order to re-fight the war. It's worth noting that the comic book miniseries was written by Mac Walters, whereas the original game was written by Drew Karpyshyn.
In The Legend of Zelda: A Link to the Past there was mention of Seven Wise Men who sealed Ganon in the Sacred Realm. Ocarina of Time and every other game in the series, retcons them as "The Seven Sages" in which most of them were in fact female.
For the first time in the series, Animal Crossing: New Leaf introduced two new villager personality types, Smug (for males) and Uchi (for females). While most of the villagers with these personality types were created for New Leaf, some villagers from previous games got changed, like Charlise (Peppy → Uchi) and Kidd (Lazy → Smug). A small few island villagers from the first game also had their personalities changed when they were introduced as regular villagers in later games, such as Rowan (Cranky → Jock).
The king of all retcons is the webcomic Sonichu. The creator was trolled by people pretending to be Shigeru Miyamoto, who was talking to the creator, Chris, about a game development. When this troll said that would be impossible to make a game based of fanwork, another troll, posing as a lawyer pretending to be Jay-Z, advised Chris to change several aspects of the comic. What followed were so many terrible retcons, there's a whole Wiki about it. The weirdest part is that the creator actually believed he was in contact with Shigeru Miyamoto and Jay Z the entire time.
R.H.Jr's 'Goblin Hollow' had the hell retconned out of it. It was once known as 'Under the Lemon Tree' and the Goblins were originally figments of Ben's imagination made real. It received a retcon changing the setting, and quite a few facts from the original, including how the goblins came to be.
Gunnerkrigg Court contains a minor retcon. In the first chapter, Antimony reconstructs a robot from spare parts in order to carry a shadow across a bridge (it was the only logical answer). To many, this implied that she was at least somewhat technologically proficient, as she is able to look at a piece of what we assume to be complex machinery and repair it almost completely. However, as the comic continues, we learn that her best friend Kat is actually the scientist and Antimony is perplexed by machinery if anything. So, how did she rebuild a complicated gizmo like Robot? Well, we learn that all she really did was snap his fully functioning joints together (showing she is at least familiar with the "Head bone's connected to the neck bone" song), and didn't actually need to mess with his hardware to reboot him.
Erfworld needed to retcon a special ability given to one of the characters in its series. Funnily enough, it actually managed to successfully lampshade this through the ironically-recursive introduction of a school of magic known as retconjuration. (In an even more delicious twist of irony, this school retroactively replaced a school called Deletionism, which was itself deleted.)
Drowtales went through this once. Now the first episode has been redone the second time. While the new pages are much better quality-wise, and some of the plot make a lot more sense, many elements were removed, characters have been changed, and episodes were cut down to mere sketches of their former selves. Not to mention the mysteries the reader was left in the dark about for most of the original stories were also revealed retroactively. The series also became Lighter and Softer in some ways while amplifying some of the darker themes at the same time.
In a 2003 Penny Arcade strip where Tycho volunteers as a Mall Santa at a pet store, Gabe mentions that Tycho hates animals. Years later, we would find out that Tycho loves animals, and is sexually attracted to them.
Discussed in an "Ammika Explains" segment of APT Comic.
In 8-Bit Theater, shortly after becoming a ninja, Thief decided that his original ninja outfit didn't do it for him. So, proving his mastery at his trade, he stole all images of the older design from the comic archives, replacing them with the later outfit.
From the V3 Pregame to the start of the game itself, Sean O'Cann went from a narcissistic, arrogant Jerk Jock with hints of homosexuality to a friendly, compassionate, fairly sensitive guy. This change seems to rely on the assumption that a couple of pregame topics (which featured Sean acting like a Jerkass) never happened.
Bobby Jacks' full name. It transpires on the 7th day of the game that his name is actually Robert, with Bobby being a nickname. No reference of this being the case had been made before this point, although some people assumed that his name was Robert prior to that, but it's never mentioned, and his profile doesn't even note it.
Finally, the setting itself was Retconned, changed from being set in the Battle Royale universe to its own original continuity and setting.
Lampshaded in Unforgotten Realms where in one episode, Garry got his original body back (in a way that doesn't make sense), and jumps off a cliff. Two episodes later, Roamin talks about how the show does not make sence, and Garry reappears in his new body.
In the Homestar Runner toon "email thunder", it turns out that Homestar has had his own email-answering program for a while now. Much of the time when Homestar appeared incompetent or insane was merely part of his show. Not only that, but his show is actually more popular than Strong Bad's. This is expanded upon in "Hremail 7", where it's revealed that Strong Bad first got the idea for his show from Homestar and then forgot about it. Also, he got his first computer from Homestar's trash, and his first email was actually sent by a friend of The Cheat's.
Orion's Arm has made a number of retcons since it's creation. Femto-tech was removed due to physics problems. The number of people killed by GAIA was retconned a number of times in order to adjust the population numbers.
While not happening all the time, it is not uncommon for certain characters to be retconned in Marvels RPG. This will mainly happen if a new member wish to use a scrapped character that haven't done much before (s)he was scrapped.
The My Little Pony: Friendship Is MagicFan Fic "Pattycakes" was first written so that a badly derailed Fluttershy broke Rainbow Dash's will and caused her to regress to a childlike mental state. Given that a) the psychological torture involved consisted of bondage mitts, oatmeal, a bottle and a nappy and b) the whole thing took less than a day, a second part still referred to Dash as "mentally broken" but hung part of the plot on Dash's condition being the result of a mental regression drug Fluttershy had invented.
Whateley Universe: Word of God says that the author of the Phase novels only started years after the series started, and reinterpreted everything she didn't like about Phase's behavior in such a way that there were no outward changes (everything in prior stories was 'right' or 'slightly misheard') but all of Phase's actions were explained.
Less forgivable is "The Review Must Go On". Context: To Boldly Flee was meant to be the Critic's swan song, where he spent most of the special locked in depression and only really become happy when he became the Plot Hole. After that, there was a new show called Demo Reel, led by a tragic Former Child Star called Donnie DuPre. Five episodes of that went by, and "The Review Must Go On" suddenly made it out of nowhere that "Critic couldn't comprehend the selfless act he performed" and Donnie's terrible life was just a punishment for him formed by purgatory. To say it was an Ass Pull is an understatement.
Benthelooney is a prominent abuser of this since his rants were Un-Cancelled. From the original dubs to the first half of the "Revival Era", he was fairly consistent for the most part with his opinions and stuck with them. But in the middle of 2012 to this day, he started retconning his original opinions on subjects that were mostly well-established later on(Pixar, and even Adventure Time and Regular Show).
In a season two episode of Avatar: The Last Airbender , Ozai and Iroh's father Azulon is said to have been Fire Lord for 23 years before Ozai and that Fire Lord Sozin ruled for the first 70 or so years of the 100 year war. The Nick website also provided a brief backstory for Sozin saying that he was a young man when became Fire Lord shortly before Roku died and was prevented from starting the war until the elder Avatar Roku's death. Come season three where it's revealed that Sozin and Roku are actually the same age and that he was an old man when he started the war. In response, the creators revealed that Sozin ruled for only the first 20 years of the war before Azulon took over for the next 75 years before Ozai became the Fire Lord for the last 5 years. This has caused confusion for many fans.
Futurama, "The Why Of Fry". This fourth-season episode posits that the original accident causing Fry to be frozen and sent forward into the year 3000 was actually intentionally caused by Nibbler and the Nibblonians so that he could save the universe from the giant space brains. At first glance, this seems like a retcon; however, careful viewing of the original first episode shows the shadow of Nibbler underneath the desk as the accident happens and in a revisited scene his eye stalk poking out, proving that the producers of the show set this up from the very beginning.
In Lethal Inspection, we see the real story of Bender's birth after he told a different version. Rather than being born full-sized just a few years ago, he was born as a baby-shaped robot with a visibly-younger Hermes as his inspector. Completely worth it for that song.
Bender caused the alien apocalypse we see in the first episode.
One of the biggest retcons was the episode "Where No Series Has Gone Before." where it is revealed that it is illegal to even mention Star Trek. Virtually every episode before that had at least on Star Trek reference. When Fry meets Leonard Nimoy at the Head Museum he calls him "Spock". When Fry is confused by the DOOP, Hermes says it's like the Federation on Star Trek.
Kim Possible: While it was never mentioned in the show proper, the Word of God in the beginning was that Shego's plasma hands were due to some technology in her gloves, which matched with how her powers were used in first season episodes. She was eventually turned superhuman, shown using her abilities barehanded, and even given a Super Hero Originbackstory. Note that the official website still has the original explanation.
The Justice League cartoons get rid of most of the annoying retcons in The DCU, but they make a few new ones. Doomsday showed up in the original Justice League episode "A Better World," in which he said he was an alien invader looking to see what Earth had to offer in the way of worthy opponents. He's never heard of Superman before and doesn't seem to care one way or another about him. Later on in Justice League Unlimited he was retconned to be a creation of Project Cadmus, who reverse-engineered him from Superman's DNA and conditioned him to hate Superman above all else. Then, to explain his appearance in the older episode, Cadmus shot him into space for no good reason. He even got a completely different voice.
It happened again in the Fully Absorbed Finale for Batman Beyond, which threw together plot points from dozens of episodes and two movies into something they clearly weren't originally meant to be. It's cleverly pulled off, though, as any potentially created inconsistencies are rather smoothly Hand Waved by a line from the creators, stating that their choice to have Bruce Wayne revealed as Terry and Matt's biological father was partly motivated by them realizing how Terry and Matt having black hair is genetically improbable since Warren's hair was light-brown and Mary is a redhead.
In The Simpsons, the series has gone through a retcon as of the episode "That 90's Show." In the earlier episodes, Homer and Marge attended high school in the late 1970's got married three or four years after graduating from high school after Marge became pregnant with Bart, Bart was born in 1980, Lisa was born in 1983, and Maggie was born in 1990, but the series was retconned in the aforementioned episode. Marge in previous episodes had never gone to college, but was suddenly attending in the mid 90's; it led us to believe Homer had a Grunge band, whereas in an earlier episode he didn't understand grunge at all; and they also showed us that they dated for at least ten years before getting married and having the kids, who are now retconned into being born in the early 2000's.
Prior to this the characters were stuck in the 90's and never aged.
The Simpsons time line being what it is, this retcon actually makes sense. The Simpsons' time exists on a sliding line, so even though every episode happens in "the present", the past keeps moving forward. Also note that while the kids' age never change, Marge and Homer have been, albeit very slowly, getting older; being in their mid-thirties in early episodes and now nearing forty (presumably to reflect the aging American population), which does leave a gap for the events of "that 90's show" to take place.
The writers have made clear that some things are immune to the sliding time gimmick. Grandpa Simpson and Mr. Burns will always be WW2 veterans, even if that makes them unrealistically old. They will also have both known the Great Depression.
Also on the subject of Mr. Burns, he started out at 81 years old (the early episode where Homer defrauds the plant's health insurance for hair growth), but is now canonically 104 years old.
Mr. Burns had been mentioned to be 104 as early as season 6. Although, his age is basically debated, many of his other mentioned possible ages place him as being older than 104, some place him at 118, others at 122.
Unrelated to the sliding timeline, one glaring aspect that was essentially retconned from the show is Homer's relationship wtih his mother. In the fourth episode, "There's No Disgrace Like Home", Homer mentions that his mother said he was a big disappointment. However, if "Mother Simpson", "My Mother the Carjacker", and "Mona Leaves-a" are any indications, Mona Simpson has always loved Homer and it's doubtful she would've ever said anything of the sort.
Likely a case of Characterization Marches On, given that it occurred so early on in the show's run (same episode has Homer pawning the TV set so that his family can learn some manners), and very little was made of their relationship in between. Arguably, it was a retcon for "Mother Simpson" to establish that Mona had been alive all this time, when it had been implied up until then that she'd died, but then the details on Homer's mother had always been very vague.
As for the whole 90's ret-con, it helps to clear up one glaring Plot Hole that Jon Stewart once pointed out to Matt Groening in an interview. Homer and Marge were supposed to be in their late 30s. They got married when they found out Marge was pregnant with Bart, but since Bart is only 10, about a decade would had to have passed between high school and Bart being conceived. Lisa even lampshaded said plot hole in the episode.
Even that was a retcon. In the early seasons Marge and Homer were 34 and in Season Two (1990) it was revealed they graduated in 1974, giving them a birthdate of 1956. Bart was born in 1980, six years after they started dating. The retcons started happening fairly fast though. By Season Four Lisa was given a birthdate of 1983 and Bart was said to be two, giving him a birthdate of 1981 but in the same season Marge and Homer were still part of the 1974 class.
King of the Hill: In "Death Picks Cotton", when Cotton tracks down Hank and company in a Japanese restaurant, it triggers his flashback, and he calls the Chef (who only speaks Spanish) a Tojo. However, part II of "Returning Japanese" had basically been about him forgiving the Japanese, and he was talked out of his scheme to spit in the Emperor of Japan's face by his illegitimate son Junichiro, resulting in apparent Aesop Amnesia.
Peggy's background was rewritten so that she spent most of her early life in Montana, rather than spending her high school years in Arlen. This complicates the episodes where Hank and Peggy are shown as High School Sweethearts. Meanwhile, Peggy's mother changed from an older-looking version of Peggy who was just hyper-critical into a totally different looking woman who was a downright bitch.
Luanne's father/Peggy's brother didn't appear until near the end of the series, though was mentioned several times. Originally, he had fled to an oil rig in fear of his abusive ex-wife, refusing to come back on land until Hank faxed him her death certificate. Bill mentions him looking like a male version of Peggy while Hank mentions getting along with him. When he shows up, however, he is revealed to have actually been in jail for years for being a con artist and thief, a fact which Peggy hid from everyone with the oil rig story. He also looks nothing like Peggy and it seems that Hank had never met him before. This change calls forth several bits of Fridge Logic: one, Luanne is supposed to have seen the event that caused him to flee to the oil rig; how does his incarceration fit into that event, especially since we know her mom was put in jail herself for that abuse? And if she was already in jail, why did Peggy (and later Hank) think it would be so traumatizing for Luanne to also know that her father was as well? Also, they established several times that Luanne witnessed the fight between her parents that led to her mom stabbing her dad with the fork which occured in the very first episode where she was about 16 or 17, but in this episode her dad claims the last time he seen her she was a little girl about five years old and she has no memory of the event.
Hank and his old Arlen High School football team challenged the team that they lost against during the championships to a rematch that they eventually win. This one is made more annoying by the fact that Hank had come to terms with losing the game in an earlier episode. It left a bad taste considering it was one of the last episodes.
Another would be the origin of Dale's Rusty Shackleford identity, in a couple of early episodes he mentions he got the name from a boy who died from smallpox back in the 1950's, however it was later retconned in the season 11 episode "Peggy's Gone To Pots" where he supposedly got it from a boy who went to his school and moved away and Dale thought he died, and the "real" Rusty Shackleford arrives to tell him to stop using his name.
Thomas the Tank Engine: Reverend Awdry stated that the North Western Railway was built in 1914, mainly by Edward. In the 2009 movie Hero of The Rails, it is stated that the new characterHiro was responsible for building it. This may sound like a standard Ret Con, but keep in mind that Hiro is a JNR class D51, which wasn't built until 1936. And it doesn't help that Hiro is Japanese and thus runs on a completely different gauge than traditional British engines...
Dexter's Laboratory: in the fifth episode we are introduced to Dexter's rival, Mandark, who had just moved into the neighborhood as an exchange student. He introduces himself as Astrononminov (Possibly his last name, but prefers to be called Mandark. He was a fairly competent villain, at least when Dee Dee wasn't around, and he had a sister named Olga Astrononminov that prefers to be called "Lalavava". In the last two seasons (made after a production gap of a couple years), Mandark is now named Susan and has a pair of hippie parents. He and Dexter supposedly first met when they were little, and he became an incompetent villain because Dexter made fun of his name.
Not to mention Olga seems to have been forgotten by the writers entirely aside from her one appearance.
In the original The Fairly Oddparents pilot, Vicky was apparently babysitting Timmy for the first time, and Timmy was ten. The first movie reconned both points: Vicky had been Timmy's babysitter for a year, and Timmy was nine when he first got Cosmo and Wanda.
In the Jonny Quest made for TV movie Jonny's Golden Quest, Jessie was revealed to be the daughter of Race Bannon and his mysterious lover Jezebel Jade, during a brief affair the two had. In the second season of the next series The Real Adventures of Jonny Quest, the new writing staff created the character of archeologist Estelle Vasquez to be Jessie's mom (and Race's ex-wife) since they believed Jade wasn't the kind of woman who would settle down.
Jesse Bannon herself was a retconned version of Jesse Bradshaw, a character who appeared in an episode from the 80's series The New Adventures of Jonny Quest. The original Jesse was not related to Race Bannon.
In the Ben 10: Alien Force, episode "Be-Knighted" the evil group the Forever Knights has their Villain Decay cemented when it's revealed that their ultimate goal was no more than to slay some poor alien dragon they had captured as opposed to conquering the world, as they had attempted in the original series (they even had a different leader than was seen in the older series as well) because they're knights and, well, slaying dragons is what knights do. When Ben and company helped that dragon escaped, they decided to eventually travel to that dragon's planet to try and wipe them out. Series writer/producer Dwayne McDuffie later revealed this was, in fact, their goal from the beginning and the Forever Knights Ben fought in the original series (led by former Plumber Driscoll as the "Forever King"), was actually a rogue splinter faction of the original group and that the king Patrick, seen in "Be-Knighted", was the true Forever King and Driscoll was an imposter, or something.
Then, we get Ultimate Alien, which changes it again. There are in fact many factions. Driscoll's was one, the ones literally Bullying a Dragon were another, but all were considered as having lost their way by the true founder, who returns and brings them all together (in an episode in which we see every Forever Knight leader from the past, all of whom are willing to follow the First Knight once he proves he's who he says he is.) Their original goal was to get rid of an Eldritch Abomination called Diagon, but they seek to remove all"alien scum" from the Earth. This results in a Darker and Edgier arc beginning, where Diagon is the ultimate evil in the series and the Forever Knights are a very competent foe (and help in episodes related to their common enemy.)
There's also changing the nature of Gwen's magic due to being part alien and turning the Plumbers from a defunct federal Men In Black-esque agency into a still-active intergalactic police force.
Also, Kevin has his past added onto to make the complete overhaul of his powers and personality between the original series and AF/UA make at least more sense than it did originally. Also part alien; has the earlier energy powers and the new matter powers, but using energy makes him go nuts, making for the Kevin of the original series.
The Season 14 episode "201" retcons the twist ending of "Cartman's Mom Is Still a Dirty Slut", from way back at the beginning of Season 2 (twelve seasons before) by revealing that Liane was Cartman's mother all along and her claim of being a hermaphrodite was simply a cover-up to protect the identity of Cartman's real father, the former right tackle of the Denver Bronco. Said Denver Bronco turns out to be none other than Jack Tenorman, the man Cartman murdered and fed to his son Scott in the Season 5 episode "Scott Tenorman Must Die". Cartman seems more upset at the fact that he is Scott Tenorman's half-brother, thus making him half-ginger, than with the revelation that he killed his own father and then fed his remains to Scott.
He feels better when Mitch Connor reminds him of the fact that he's also half-Denver Bronco.
South Park also gives us what is possibly the most epic retcon ever. In the second episode of the "Coon and Friends" trilogy, Kenny reveals that he can't die. He explains to another superhero that he's died many times in the past, and just ends up waking up in his bed like nothing happened, the only one who remembers his gruesome demise.
In the episode "City Sushi", Tuong Lu Kim the Chinese resturant owner is revealed to be another personality of Dr. Janus, a doctor who suffers from multiple personality disorder. In his past appearances, he was portrayed as an authentic Chinese man.
In "Mr. Hankey The Christmas Poo", it's established that Kyle's family are the only Jews in South Park. Later in "The Passion Of The Jew", we see a Jewish community large enough to have a synagogue (though the synagogue first appeared in "Cartmanland").
Lampshaded in the 9th season Family Guy episode "Excellence in Broadcasting": When the Griffins hear that Rush Limbaugh is coming to town to promote his latest book, Chris recalls that, during Lois' brief stint at Fox News (in the "Foxy Lady" episode), she reported that both Limbaugh and Michael Moore were characters played by Fred Savage. Lois dismisses this, explaining that even if something is true is true to begin with it becomes a lie when said on Fox News.
The episode "Brian: Portrait of a Dog" shows Peter adopted Brian as a stray when he was washing people's cars to earn money, however "The Man With Two Brians" shows the Griffins got him as a puppy.
In the fourth episode of American Dad! it is stated that Roger has been living with the Smiths for four years since Stan rescued him from the C.I.A., however in a much later episode there's a flashback of Stan giving him to Steve as a little boy for his birthday.
In a flashback from "White Rice", it was shown that Hayley once has a twin sister named Bailey who is implied to have died because Stan didn't allow them to get vaccinated. This goes against an earlier episode that showed Hayley as being a single birth (though that could have been a throwaway gag to make Stan look bad).
Played for Laughs in "Stan's Best Friend", wherein Stan refuses to let Steve get a puppy:
Lampshaded in Frisky Dingo. In one episode, Grace Ryan is seen taking "Ret-Con" brand ant poison to cure herself of her Superpowered Evil Side Antagone. In another episode, it's explained that the Annihilatrix has been completely rebuilt, despite previously having been stripped down for scrap. A quick cut shows that the rebuilding was done by "Ret-Con" Construction Company.
In the Rocky and Bullwinkle story "Missouri Mish Mash", this occurs within the same story. At first it's said that the Kirwood Derby has been around since the Stone Age. Later on however, it's said that the derby was created for an otherwise idiotic moon prince.
The Arthur episode "Arthur and the True Francine" showed that Muffy first came to Elwood City when the others were in second grade. However, the first season episodes are filled with Early-Installment Weirdness which was later ignored. Brain's Shocking Secret showed that Muffy has been in Elwood Ciy since kindergarten.
When Morph is revealed to be alive in season 2 of X-Men, the flashbacks of his survival don't match the events of "Night of the Sentinels". In the original pilot, Jean telepathically senses Morph getting shot by the Sentinels and, only seconds later, Xavier tries to reach him, only to find no trace of his mind, implying he's dead. Meanwhile, it's shown that the X-Men were under siege by the Sentinels for at least several minutes before deciding they couldn't help him (or an also injured Beast) and reluctantly retreating. In the season 2 flashbacks however, Morph is shown to be still alive until after the X-Men leave.
It's even worse in the X-Men Adventures spin-off comic. The second issue gives Morph an on screen death (something the cartoon never did), with Beast by his side, and even subtly explains what happened to his body (it was seemingly never found in the show). When season two rolls around, they just flashback to Sinister carrying him to safety, without ever explaining the inconsistencies with issue two.
Fillmore!: episode 3 has Ingrid learn about Fillmore's delinquent past. Episode 8 establishes in flashback that he told her about it before even recruiting her to the Safety Patrol. It's unlikely Ingrid forgot, given that she literally has an eidetic memory.
In athletics it is common to strip an athlete or even an entire program of its honours and records retroactively if the subject is found guilty of a serious enough violation. The justification for this — especially in cases of doping, match-fixing, or bribery — is that an achievement which did not occur on a fair playing field was never an achievement to begin with.
All of cyclist Lance Armstrong's results from after August of 1998 were wiped from the official stats in 2012 when evidence that Armstrong had engaged in systematic doping came to light. Among the titles he lost were 7 Tour de France victories, an Olympic bronze medal, 2 Criterium du Dauphiné victories, and a victory at tour of Switzerland.
Amongst other punishments meted out by the NCAA, all 112 of Penn State University's football victories between 1998 and 2011 (including 5 bowl games) were scrubbed from the official records after it was revealed that university officials had helped cover up an assistant coach's involvement in child sexual abuse. As a result, former head coach Joe Paterno lost his status as the winningest Division I head coach, dropping from 349 victories to 237.
In both 2005 and 2006, Juventus won Serie A, the top football (soccer) league in Italy. Then the story broke that it was one of four teams involved in many instances of match-fixing. The 2005 season was simply wiped from the record books, and the 2006 title was awarded to third-place Inter Milan after Juventus and second-place AC Milan were disqualified due to the scandal.
Stalin was constantly re-writing the history of the Communist revolution and the early USSR to take credit for opponents' accomplishments or to ghost them out entirely, even when the resulting narrative made no sense. A few of his successors continued the practice. Stephen Jay Gould once reported reading a version of the Soviet Encyclopaedia that completely removed Stalin from history, which is kind of like trying to sell the Star Wars original trilogy as "The Jabba The Hutt Show!"
He's also known to have ordered the doctoring of images, although the manipulation now looks pretty crude. One can find photos where Trotsky and others Stalin had killed have been removed, and other photos where he is shown next to Lenin as the latter fell sick and died (even though at this time Lenin had started to dislike Stalin).
Similarly, it was rumored during the space race that many Soviet cosmonauts had actually perished on failed missions, then were edited out of the group pictures taken with the equipment. In reality, there's no concrete proof of earlier, failed missions, but there IS proof of cosmonauts edited out of photos after public disgrace or loss of political favor.
The 2006 reclassification of Pluto as a dwarf planet retconned decades of science textbooks. It was starting to get embarrassing as more and more trans-Neptunian objects were discovered that were of a similar size (one of them, Eris, is larger) but were deemed too small to call planets. The main argument for keeping Pluto in the class of planets was "cultural" (read: sentimental), so the "dwarf planet" term was a cultural compromise with a scientific bonus. Culturally, Pluto's significance as the first Kuiper Belt Object discovered and as one of the largest was still recognized (it became the Trope Namer for a new sub-class of KBOs / dwarf planets, the plutoids). Scientifically, Pluto was no longer complicating the IAU's terrestrial planet definition and the "upgrade" of Ceres from asteroid to dwarf planet resolved the paradox of the latter being the only Asteroid Belt Object massive enough to have overcome hydrostatic equilibrium and taken on a spherical shape note Ceres alone represents about a third of the total mass of the Asteroid Belt. Like Pluto, Ceres was considered a planet when it was first discovered in 1801 but "downgraded" soon afterwards when other large objects were found in the same general orbit.
In 1660, the restored Royalist regime in England declared that the eleven years of republican rule had been "invalid" since no monarch had been there to give assent to the various laws parliament had enacted. A legal fiction was created where Charles II's reign was backdated to 1649 and the 1649-1660 Cromwellian era was described not as a republic but as an "interregnum" (i.e. a period where a kingdom has no sitting monarch). Very few modern historians accept 1649 as the beginning of Charles' rule, but the term "interregnum" is still often used to describe the Commonwealth period even though the monarchy did not technically exist during those years.
Charles was proclaimed king by the Scottish parliament only a few days after his father's execution, and was even crowned at Scone before he had to flee to the Continent, so technically, his reign as King of Scotland could be dated to 1649. The throne of England was unambiguously vacant for eleven years, however.
Similary, the Bourbon Restoration decided to ignore both the First French Republic and Napoleon's empire. They declared the son of Louis XVI (who had been executed in the Revolution) to have been King Louis XVII despite never having ruled or even been crowned, and Louis XVIII dated his own reign from Louis XVII's death in 1795, instead of 1814, when he actually came to power.
And when Bonaparte's nephew Louis-Napoleon took over in 1852, he termed the Restoration the Second Empire, and his rule the Third. He also took the regnal name of Napoleon III, with Bonaparte's son termed Napoleon II despite never ruling.
In the early hours of April 1, 1964, the Brazilian military carried out a coup d'etát and began a 20-year dictatorship. Predictably, they retconned the date of the coup to March 31.
Henry VII officially dated his reign from the day before the Battle of Bosworth, i.e., the day before he finally became the Last Man Standing in a decades-long game of Kingmaker. This was a very smart move as he could then strip the lands and titles of any lords who'd fought on the opposite side of the battle for treason against the King. It was also an incredibly unfair one, because it meant that people fighting to defend the crowned and anointed King of England (Richard III) against a rebel (Henry) were traitors.
Common practice in North Korea, especially with the details of the lives of Kim Il Sung and Kim Jong Il and of The Korean War. One story of Kim Jong Il's birth was that North Korean soldiers stationed in the mountains near his claimed birth-site had a premonition that something wonderful was happening at the time he was born. To mark the occasion, they carved the date into a tree. This tree was then shown to visiting foreigners... until a Japanese botanist pointed out there's no way anyone could have carved something in that tree on that date because the tree was not old enough to have existed at the time. The tree was silently cut down and never referred to again.
Some automobile magazines do not consider the Volkswagen Logus to be in continuity with the Ford Escort line, despite being related to it. Why say it's not related, when it uses an adaptation of the Ford Escort chassis?
After World War II, French President François Miterrand (a former member of the Resistance) declared that the Vichy Regime had never been more than a puppet government and Charles de Gaulle was to be recorded as the true and rightful head of state for the duration of the war, even though he spent four of those year in exile in England. This has not prevented many later historians from debating which city was functioning as the true wartime capital of France, London or Vichy.
Pope Gregory XIII decreed that the day after Thursday, 4 October 1582 would be not Friday, 5 October, but Friday, 15 October 1582. This was due to a miscalculation of days in the Julian calendar that had caused the Vernal Equinox to seemingly change from the traditional March 21 to March 11. Since the Church scheduled Easter based on the first day of Spring, the retcon was seen as necessary.
Commonwealth countries that recognize the British monarch as head of state, such as Australia and Canada, originally did so as colonies, as it was only natural for the ruler of the imperial power to also be the nominal head of all colonial governments. As the colonies became more autonomous and self-governing, imperial law became more complicated, and when Elizabeth II ascended to the throne, she was proclaimed to be the independent queen of over a dozen independent monarchies (ie; Queen of Australia of the Australian monarchy), rather than the imperial British queen. Commonwealth countries now frequently retcon old British monarchs in this way ("Former Kings of Canada") which further muddles the evolution of the relationship.
Furthermore, the queen's regnal name in all the countries she reigns over is 'Elizabeth II'. With the possible exception of Canada (there was a tiny English settlement in Canada during Elizabeth I's reign), she is the first monarch called Elizabeth in all her countries except Britain itself (and even that doesn't hold true in Scotland).
When Seti I created the Abydos kinglist, which listed all of Egypt's pharaohs from King Menes, several were conspicuously missing: Hatshepsut, who had been retconned after her death by Thutmose III; Akhenaten, the Heretic King; and Tutankhamun and Ay, presumably because of association with Akhenaten. Instead, Horemheb's reign dates from the end of Amenhotep III's.
40 years after Hatshepsut's death, Thutmose III tried to erase all evidence that she had ever been pharaoh — we don't know why, but it may have been that a female pharaoh shook up the status quo too much.
The Brazilian football championship officially started in 1971. Then in 2010, the Football Confederation decided to turn winners of twoprevious tournaments Brazilian champions as well... even if it meant two winners in two years (as both those tournaments had editions in '67 and '68) and champions with only two games.
In 2006 Sun dropped the major version number on Java to better reflect the maturity, scalability, and security, of the Java platform. Java 1.5.0 became Java 5. In addition, Sun reverted the names of the the run time environment and development kit. The Java Development kit went back to JDK from Java 2 SDK and the run time environment went back to JRE from J2RE.
Before World War I, "The Great War" referred to the Napoleonic Wars. Similarly, before 1991, the "Gulf War" referred to the 1980-88 war between Iraq and Iran.
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