DVD menus are also a great place to spoil huge twists (even though they're usually twists that are already known by anyone with basic familiarity with the movie or show).
The DVD/Blu-ray menu for the Doctor Who anniversary special "The Day of the Doctor" features the closing credit sequence of the episode (sans credit text), revealing the outcome for a major character in the episode. It also acts as a spoiler regarding a mini-episode called "The Night of the Doctor" which is also included in the set. And it's not a case of "just ignore it" because the closing credits feature a new and unique rendition of the theme song that is bound to cause some viewers to stay tuned.
The Wire's S2 DVD's episode description has a picture of D'Angelo getting strangled, spoiling that Stringer ordered his death.
For example, to watch The X-Files episode "End Game" you have to click on a still from the episode showing Samantha Mulder's face bleeding green blood, revealing not only that the Samantha featured in this and the previous episode was fake, but also that she dies.
The X-Files has in both menus and the short video that starts the DVD (for instance, in Season 6 the very last scene of the season - a Cliffhanger, of course - is used in both).
24 Season 2 relies on your knowledge that Nina was the mole and killed Teri Bauer.
David Palmer dying at the start of Season 5 is spoiled on the back of the DVD collection, as is Jack faking his death at the end of the previous season.
Tony's return in season four was meant to be a surprise. Which would have worked better in Scandinavia, had the DVD box set not featured him on the actual disc covering episodes set before he actually shows up.
Also, Tony being not quite dead in season seven must have been one of the worst kept secrets of all time.
Watch Live Another Day before any of the other seasons in the series? Congratulations! You just spoiled for yourself that Jack becomes an international felon on the run from the law at the end of the show's original run.
Agents of S.H.I.E.L.D., being set in the Marvel Cinematic Universe, contains spoilers for Captain America: The Winter Soldier in the episode "Turn, Turn, Turn." If you watched the episode before the movie, the twists that HYDRA is controlling S.H.I.E.L.D., S.H.I.E.L.D. is ultimately disbanded, Captain America has disappeared and Nick Fury is allegedly "killed" are exposed. What makes this a particularly nasty example is the episode in question aired only four days after the movie debuted, meaning a good percentage of the audience wouldn't have had a chance to see it yet due to sold out theaters on the opening weekend. The Tag at the end of the previous episode, "End of the Beginning", was a scene from the movie which was happening at the same time as the episode, so they did attempt to give fair warning. This is one of the pitfalls of tying in so heavily with the movie (though there was no way to avoid it and neither would be nearly as good without it). If you watch the show first, the HYDRA takeover is no surprise once you see the movie. If you watch the movie first, it's no surprise when you see the show. It's a bombshell in both.
Alias has the big twist of the first season finale (that Sydney's mother not only is alive, but she is evidently the Big Bad of the show up to that point) ruined by the covers of the DVD's for the second season. And the twist for the second season's finale is also detailed in the back covers for the third season DVD's. And the covers for the fourth season DVD's prominently feature Nadia, Sydney's half-sister and whose existence was also a secret in the third season. It's almost a miracle that the fifth season DVD covers do not reveal anything about the show at that point.
Arrow has spoiled the fact that Malcolm Merlyn survives his "death" in the first season finale, what with him appearing in trailers for later episodes and his actor getting promoted to series regular for the third season.
In the first crossover episode in The Flash (2014), they casually mention Sara's death a few times.
In the second crossover, Felicity mentions Oliver potentially joining the League of Assassins, Laurel being the Black Canary, and Thea training with Malcolm, all of which are significant spoilers for Arrow's third season.
The penultimate episode of The Flash's second season spoils the death of Laurel Lance/ The Black Canary in Arrow's fourth season.
The trailer for the then-unaired second season spoiled the major twist of the previous season's finale (Commander Adama being shot in the CIC) in its very first shot, while blatantly spoiling several other elements (Why is Boomer wearing a bandage over her cheek? Why is Gaius Baltar lying injured on a planet? Why is Starbuck with Helo and Sharon all of a sudden? Why are Lee Adama and President Roslin in a brig?) And, even though Adama is shot, he still appears (uniform and all) on the DVD cover art for the second season.
The season 3 trailer spoils the fact that most of the fleet has settled on New Caprica, and that Tigh is missing one of his eyes.
The fourth-season trailer begins with, "Last season Starbuck Returned...4 Were Revealed", before showing the faces of the four Cylons whose identities were (up to that point) a secret.
Roslin's terminal cancer doesn't stop her appearing on the cover of the final series DVD boxset.
Black Mirror: The Series One plot twists are not hidden, but it is now relatively common knowledge that the Prime Minister fucks a pig without needing to, that Abi ends up a drugged-up porn star, and that Ffion is a cheater. Twists from the later seasons have been more closely-guarded, but then people may still be catching up.
A trailer for the fourth season of Blake's 7 on the third season box set largely consists of lengthy detailed clips of the Seven being gunned down by Federation troopers. This is the very end of the series.
Also, the show didn't feature the full original Seven until the fourth episode, meaning the first three episodes feature an awful lot of Decoy Protagonists who look like they're going to be accompanying Blake long term only to be killed off in their first appearance. It is hard to imagine anyone watching the series now without knowing who's really a regular and who isn't, especially when DVD and VHS releases tend to have publicity photos of the cast splashed all over them. (The second VHS release of the first two episodes took this to the extreme, by including a photo of the original Seven when one of them isn't even in the first two episodes.)
Near the beginning of the third season, Avon is captured by a group of Federation troopers, only to realise one of them is slowly picking off all the others. The solution is extremely obvious if you're familiar with the regular cast for the third season and thus know the significance of that Tarrant guy.
Bones: the fact that Sweets is killed in the season 10 premiere was spoiled when a BuzzFeed post about it appeared not long after the episode was aired in the US. Needless to say, many people were upset, as even the title of the article was a spoiler. One person even commented that "if people didn't watch the episode when it came out, it's their own fault" and was promptly met with replies stating that it had not (and STILL hasn't) aired everywhere else.
The official Breaking BadFacebook page posted a memorial picture about Walter White's death shortly after the series finale. Fans were outraged, and it was removed in about a day. (Yahoo! also posted one, and it stayed). And commercials for the show on AMC spoil Gus's death.
The big twist in the first season, that Angel is a vampire, is pretty lame if you've seen any other season, or any preview for his own show. In the DVD CommentaryJoss Whedon mentions that he was surprised that so few people figured this out before The Reveal, as he assumed everybody would.
Likewise, Angel's fate is spoiled from the beginning. You know any deaths or Face Heel Turns he undergoes in Buffy will have to be temporary.
Any episode of either show where characters mention events on conversations that took place during their guest spot on the other show, usually making vague enough references that you can usually get the gist of what happened.
In the commentary track for the very first episode Joss Whedon mentions that the school is blown up at the end of the third season.
A commentary in the first season spoils the fact that Harmony becomes a vampire several seasons later.
UK channel Sky One ran previews for the season five finale which showed Buffy's gravestone, running it constantly so that everyone watching TV would know how the episode ended.
Many of the DVD menu screens manage to give away the episode's reveal in a single image.
The DVD boxsets tend to be spoilerriffic in their own right. Buffy's season 7 set, for example, prominently depicts Xander wearing an eyepatch; the season 6 DVD boxset reveals the main villain Dark Willow on the front cover; Angel's season 5 shows Illyria and Spike.
The first half of Burn Notice Season 2 ended on September 18th, 2008 on a cliffhanger; the bad guys try to blow up Mike. His fate is unknown. The trailers for the second half of the season, airing January 22nd, 2009, clearly show the cliffhanger. Said trailers started airing in late October. Said trailers were also airing during the catchup marathon before the episode.
Canada's Worst Driver Ever brings back the worst drivers from past seasons, thus spoiling many of them. Unfortunately, for those watching on Netflix, it's a case of either not watching or just having to live with it, since it's one of only two seasons available.
Season 13 makes frequent mention of how one of that year's nominators was themselves Season 11's Worst Driver.
Watching any given Charmed episode starting from season 4 might make you wonder where Shannen Doherty's character Prue is. It's not really a secret or a shocker anymore that she get's McLeaned at the end of season 3.
One of the reasons for this is that the back of the Season 3 DVD boxset gives out information on what happens to each of the three sisters that year. By a process of elimination feasible once you've gone through Season 3's first few episodes, you know who is the subject of "the untimely death of the third (sister)", a dozen or more episodes in advance.
All of the promos for Chuck season 3 show him using his super-kung fu skills, which was an out-of-nowhere twist for season two.
Degrassi: The Next Generation begins with a Time Skip that picks up with a new group of students (and the original students from Degrassi High) more than a decade after the final episode, "School's Out". If you watch the new series before the original, most of the surprises (Joey and Caitlin's breakup, Spike having a child named Emma that she has to raise on her own, Lucy's paralysis) are spoiled.
Later seasons of Next Generation spoil plot points from earlier episodes in their DVD boxart. Why yes, Jimmy is now in a wheelchair and J.T. is suspiciously absent from the episode summaries of the latter half of the series. More notably, the cast changeover (and graduation of most of the previous students) is spoiled by the DVD boxart for everything after season 9.
An inversion occurs in the Season 3 two-parter, "Father Figure". Emma goes searching for her biological father, Shane McKay, whom she believes to be a doctor. For most of the audience, it's a major shock to learn that such is not the case, but for those who watched the original Degrassi (which ended 11 years prior and was only broadcast on public television in America until TeenNick aired it to complement TNG), it's a foregone conclusion.
Season 4 of Dexter was spoiled during the ad campaign for Season 5
The DVD cases of later seasons show Dexter with a potentially-evil baby wearing a bib saying "My Dad is a Killer". Wait, Dexter had a kid?
The Dexter website describes the death of his wife at the end of Season 4, an important and unexpected plot point.
In one of the more egregious examples out there, every disc of the Season 6 DVD set features an unskippable ad for the Showtime network. That ad includes the last few seconds of the season you're about to watch, meaning everyone who waited to see it on DVD is involuntarily given the massive spoiler that Deb walks in on Dexter killing Travis Marshall.
Doctor Who has been around for over half a century and has accumulated a lot of these over the years:
Doctor Who is notorious for Spoiler Titles (especially concerning Daleks), a related trope to this. You can read more about those there.
The greater chunk of William Hartnell serials did not have story titles like most of the rest of the classic series, and titled individual episodes instead. Home video releases and general fandom consensus eventually named these stories in the serial style used for later Doctors, leading to Spoiler Title problems for anyone watching after the original broadcast. Anything could happen and any monster could show up in episodes called "The Dead Planet", "World's End" or "The Nightmare Begins", but no modern viewer would be watching those they would instead be watching the first episodes of the serials "The Daleks", "The Dalek Invasion of Earth" and "The Daleks' Master Plan".
And of course, the biggest one of all: "Oh hey, I really like this old show I've found! But William Hartnell's quite old, and I've heard this show's gone on for more than 50 years. Surely he can't still be in it? Wait a second, why's he collapsed?What's happening to him!?" Of course, the fact that regeneration became a Characteristic Trope of the show, heavily and extensively marketed, and that virtually everyone knows about it damages the shock value of this twist, as well as diminishing the conflict of the first half of "The Power of the Daleks" (could this strange man with a weird, giddy personality and a deep fear of the Daleks still be the brave Doctor we know?) and turning the Doctor's death into a sort of Foregone Conclusion rather than a Shocking Swerve. It also means his Our Hero Is Dead moments doubly don't affect us because everyone's seen the clip of him transforming into Patrick Troughton.
Both Davies and Moffat the first two showrunners of the modern series have expressed their disappointment with the virtual impossibility of keeping impending regenerations secret and thus preventing spoilers in this day and age.
Also, the first ever story has two main twists that the Doctor's police box is bigger on the inside, and that it travels through time and space. Both of which are so well-known that you can be spoiled by happening to read the entry for the word TARDIS in a dictionary.
Much of "The Web of Fear" is based around the mystery of the traitor who is working with the Great Intelligence. A prime suspect is the mysterious Colonel who suddenly arrives to take over the investigation. Is Lethbridge-Stewart the traitor? To modern viewers: of course not.
The finale of the Troughton serial "The War Games" drops the absolutely colossal plot twist that the Doctor is not a futuristic human time-traveller at all, but an alien from a Sufficiently Advanced Alien civilisation. This premise has become so intrinsic to the programme that nowadays people summarising its premise will probably begin by saying "It's about an alien..." In addition to that, the two most iconic and popular Doctors (Tom Baker and David Tennant), whose tenures codified what the show is like in the popular imagination, were the two who dealt the most heavily with the nonhuman-ness of the protagonists (Baker's Doctor was constantly used as a tool by his species, and Tennant's Doctor plays it for all the Last of His Kind drama that it is worth).
The DVD booklet for "Doctor Who and the Silurians" casually mentions the fact that, oh, and the Brigadier commits a genocide at the end on the front of the booklet. It goes without saying that this is an incredible twist if you're not expecting it, but...
"Genesis of the Daleks" deserves a mention. Anyone who knows from the New Series that the Doctor "fired the first shot" in the Time War against the Daleks will probably not be surprised when, after six episodes building up to the Doctor plotting an act of genocide against the Daleks, he can't bring himself to go through with it even if that twist wasn't in All There Is to Know About "The Crying Game" territory anyway (it's very commonly cited as one of the Fourth Doctor's best moments and is talked about as the feature of the story). Of course, you'd probably know the Doctor doesn't wipe out the Daleks from the sheer fact that stories with the word "Daleks" in the title remain common.
The DVD covers for most classic serials prominently display the monster, even if it's a huge twist:
Averted by marketing for the Fourth Doctor Adventures audios featuring the Fourth Doctor and Leela Leela is referred to consistently as an "ancient warrior", which could not befurther from the truth.
The new series is a particularly nasty example of this trope since it's so damn popular, so the marketing material tends to assume everybody and their robot dog has already seen the latest episode and happily puts massive spoilers on the DVD covers.
The Series 3 DVDs have as their main menu screen backdrop the TARDIS transformed into a Paradox Machine from "The Sound of Drums".
The DVDs of Series 4 spoil the finale rather annoying for people who only get the episodes via said DVDs from their library.
"Turn Left" and "The Stolen Earth" also both spoil the series 2 finale of Torchwood: in the former, Rose only mentions Jack, Gwen and Ianto when describing how Torchwood stopped the Sontarans in an alternate timeline; in the latter, Gwen tells Ianto that she plans on "going down fighting" like Tosh and Owen when the Hub comes under attack.
The BBC's own Doctor Who website added material to its front page revealing the Wham Episode element of "Let's Kill Hitler"that Mels is the previous incarnation of River Song virtually the instant that the episode was broadcast.
There's a particularly nasty cross-pollination example for the audio drama "Jubilee". If you listened to the audio when first released, you'd likely be totally in the dark as to the carefully obscured identity of the tortured creature in the tower until its Shocking Voice Identity Reveal but now it's promoted on Big Finish's website with a blurb explaining that "Jubilee" was adapted into the new series episode called "Dalek".
The War Doctor. His mere existence is the big twist at the end of Series 7, but just the fact of there being another incarnation of the Doctor is hard to keep under wraps, and as such it will be difficult for a newcomer to remain unspoiled for that. Heck, even the Doctor Whopage image here on TVTropes gives it away.
The climactic twist of Series 8 Missy is a female incarnation of The Master, who'd last been seen in "The End of Time" follows suit for spoiling; the Sonic Adventures side story in Doctor Who Legacy gets it out of the way right off the bat!
The cover of the North American release of Series 9, Part Two spoils that the Doctor returns to Gallifrey for the first time since he saved it in "The Day of the Doctor", which is the Cliffhanger of the penultimate episode, "Heaven Sent". Granted, the BBC itself spoiled this in press releases before the episode aired, but still.
This became quite problematic for series 10 when the return of the John Simm Master and the Mondasian Cybermen in the finale was announced months prior to the first episode. Even newbies binge-watching the show couldn't escape this as they were both featured in the teaser at the end of "The Pilot".
ANY promotional materials for the 2017 Christmas Episode"Twice Upon a Time" spoil the Cliffhanger of "The Doctor Falls": The Twelfth Doctor manages to stave off his regeneration and encounters the First Doctor just as he nears his regeneration. Starting with the first trailer, it is also spoiled not only that Bill Potts and the Doctor are reunited, but also that she's no longer a Cyberman.
Downton Abbey: Trailers and promo shots for later seasons make it impossible to avoid spoilers for earlier seasons.
For example, while the first seasons were airing a big plot point was whether Mary and Matthew would marry at all, but fans who are only just starting the show can guess how that turned out since season 4's promo material showed Mary mourning hew husband Matthew, who had died in the last minute of season 3.
It's all but impossible to discuss anything that happens in Fringe after the end of Season 1 without mentioning that there is an alternate universe.
A promotional poster for Season Two featured Ned Stark's head on a pike, a major Season One spoiler.
While the actual involvement of war and faction conflict isn't a spoiler, several Season Two promos still went into the very spoilery detail of why it happened: Robert Baratheon is dead, and Joffrey is indicted as Cersei's bastard. Granted, it's fundamental to a major arc to the series that can't be avoided, but a little tact wouldn't have hurt.
The promotional artwork for Season Three primarily featured the Targaryen dragons, also a major Season One spoiler.
The Lannisters' Twincest was a big twist at the end of the first episode. But now it's entered pop culture and is well known even by people who have no interest in the show.
If you're thinking about watching the show The Good Place, you should probably avoid watching any current advertising for the show. Otherwise, you'll realize that the characters are actually in the Bad Place, something that isn't revealed until the Season 1 finale.
In 2016, Home and Away had a big week in which two main characters were killed and a third was revealed as the culprit in a long-standing murder mystery. As soon as the episode was shown in Australia, UK magazine Inside Soap printed an article that gave away the identity of all three, over a month before UK viewers got to see the episodes. When readers complained, their response was that since the episodes had been shown in Australia they were fair game, and besides they didn't mention the characters' identities in the headline or photos, so if people read the article that was their fault (even though there was no warning that the article gave away all the details until after people had read it). Then, the week before the episodes aired in the UK, they gave away the characters' identities in the headlines and photos.
The Season 4 DVD for House has pictures of the three candidates who win the season long competition, as well as giving the actors' names. The winners weren't decided until almost the end of the season.
Season 8 of How I Met Your Mother ends with the mother's face being revealed as she buys a ticket to Farhampton. Half an hour after the end of the show, the official Facebook page posted a picture of the mother, which landed on the page of all 23 million fans of the show, most of whom hadn't seen the episode yet.
iCarly: Sam and Freddie kissed. Even more spoiled if new viewers of the show saw the trailer of "iThink They Kissed" without watching the prequel "iKiss". In said trailer, Carly yells ''Sam and Freddie KISSED!''.
Behind-the-scenes photos from the Word of God had revealed to the fandom very early on that Freddie saves Carly's life.
The Kamen Rider franchise has a recurring example with the annual Movie Wars films, which sees the current Rider joining forces with his immediate predecessor; since the predecessor's story is always a Post-Script Plot, advertising for the movies tends to spoil major late-series events, such as Koyomi's death in Kamen Rider Wizard and Kouta and Mai becoming Overlords in Kamen Rider Gaim.
Manami from the manga Life starts off as a friendly girl who befriends the depressed protagonist, Ayumu. It isn't until several chapters in that it's revealed that their friendship was a lie and that Manami is not as cute or as nice as she initially seemed. The live-action adaptation didn't try to hide that Manami is a bully. She seems suspicious from the start.
Haven't watched any of Life on Mars before you decided to check out Ashes to Ashes (2008)? Tough. Prepare to be spoiled for Sam Tyler's suicide at the end of Life on Mars, having jumped off a roof to get back to the world of 1973. One of the first images you see in A2A is Sam's file, with "suicide" stamped on it.
In the UK, the fifth season was advertised all over the place with the Spoileriffic slogan "We know Locke's dead. Right?" This sets up a unique inversion of Trailers Always Spoil for people who haven't gotten to any mention of Locke's death but have seen trailers from seasons 5 and 6, where they would have seen John Locke walking around with future cast members. The resulting confusion doesn't even really matter in the long run; if anything, it creates an authentic LOST watching experience.
The season 3 DVDs contain a booklet that goes beyond giving brief descriptions of every episode into spoiling major twists (the description of the finale mentions casually what occurs in Jack's flashforward)...which is bad, since some people wait for the DVDs to watch the show instead of watching it on air with constant breaks.
The season 4 DVD set. When you pull off the slipcover, the picture on the front of the case shows the cast, with the Oceanic 6 quite obviously darkened. Who they were was one of the primary mysteries of the first part of that season.
Also in Season 4, Harold Perrineau is credited with the main cast, despite the fact that his appearance in the seventh episode was supposed to be a surprise.
Season 5: The Journey Back.
The first name of MacGyver is a mystery until a few seasons in but is found on the back cover of the first season DVD set.
Magic x Warrior Magi Majo Pures!: Yes, Shiori was the villain in the first part of the series, but after the Magic Warriors save her, she joins them. Since she joined the team, all merchandising and promotions feature her prominently as one of the Magic Warriors.
While it was a plot twist in the original pilot, in the series proper of M.A.N.T.I.S., it's out of the way that the title character is the wheelchair-bound Miles Hawkins, using an exosuit he developed to help himself walk again to fight crime.
Minority Report (2015)'s premise hinges on spoiling the ending of the 2002 film, where Pre-Crime is shut down and the Precogs are released outside of the public eye.
Woe betide anyone who got into Misfits at a late stage and didn't want to know that Nathan dies, but turns out to be immortal and so was buried alive, thanks to E4's trailers for the second series.
MTV basically punishes viewers of Faking It and Awkward. for not watching the original Tuesday airing by downright airing 'next week' promos for each show right as the show goes to their first commercial break during weekend re-airs of each show if they watch that way.
Interested in watching the Naeturvaktin Vaktin series? You should probably know they're called Naeturvaktin (The Night Shift), Dagvaktin (The Day Shift), and... Fangavaktin (The Prison Shift). It goes without saying that the fact that the trio end up in prison at the end of Dagvaktin is an enormous twist, casually given away by the DVD cover.
NUMB3RS has one for each of the last three seasons, each related to the cliffhanger for the previous season's finale. Mostly related to season memorabilia and DVD/streaming menus.
The Season Three finale ends with Colby Granger being exposed as a traitor and arrested. But it's not hard to figure out that Agent Colby Granger will play a role in Season Four, suggesting that he will in some way be exonerated despite having confessed.
Spoils a second plot point in "Trust Metric" as well. While Don and the team are trying to figure out whose side Colby is really on, note the viewer knows the truth, but the characters aren't so sure Colby is in the hands of his target, who knows exactly where Colby's loyalties lie. The episode itself goes out of its way to preserve the suspense, so it's not until the very end that you even know if he's going to live or die (the episode actually seems to lean towards the latter). But knowing that he appears in later episodes makes it clear that one way or another, he is going to survive.
A third, more minor plot point spoiled at this same time is the question of whether or not Don is going to let Colby back on the team, a question that runs underneath the main plots of several episodes until Don makes the official announcement in the fourth episode of the season.
Given Charlie's importance to the show, the very fact that there is a Season Five suggests that the revocation of Charlie's security clearance (which prevents him from consulting with the FBI) will not be a permanent state of affairs. But the fact that several episode descriptions mention Charlie doing something with the FBI doesn't hurt either.
The Season Six premiere spends most of the episode (behind the scenes of the actual case) teasing at how Amita responded to Charlie's proposal in the Season Five finale. But the descriptions for several Season Six episodes refer to matters having to do with an upcoming wedding ("Charlie and Amita disagree on a wedding date") and the description of the series finale specifically refers to them getting married.
Jim and Pam being an Official Couple is a relatively important plot point from the fourth season onward, somewhat ruining the UST between them during the first three seasons for first time viewers.
NBC's hyping of their marriage and the subsequent birth of their first child during the sixth season solidifies this as an example of this trope.
Then again, anyone who'd watched the UK version saw it coming and knew it would eventually happen, as the UK series ends with them finally getting together.
One of the main images used by Netflix to promote the show does not include Michael, which tells that he is going to leave the show, which he does in the seventh season.
The box art for Season 6 of One Tree Hill. There was a big cliffhanger at the end of Season 5, as Lucas calls either Brooke, Peyton, or Lindsey and asks whoever he called if she wants to marry him that night. The back of the DVD box reads, "And speaking of Lucas, just which one is the right girl?"... when there are two pictures clearly visible on the back that reveal who it was: it's Peyton—the two pictures are of her and Lucas embracing in their kitchen and the background of the DVD box is Lucas kissing her in the hospital from the finale. Additionally, the network allegedly ruined the Season 5 cliffhanger by editing a promo for Season 6 in a way that made it obvious who Lucas calls, which is why Mark Schwahn, the showrunner, handles making the promotional materials now.
Orphan Black's promotional material heavily leans on the fact that Tatiana Maslany plays multiple characters (more than just the two we meet in the opening scene) and is casual about dropping that they're clones. For season three, the promos also heavily featured the Castor line of clones, played by Ari Millen, spoiling the big twist from the season two finale and identifying that a character introduced near the start of the second season is more important than he initially appears.
The Power Rangers Lightspeed Rescue crossover with Lost Galaxy has all of the original Galaxy Rangers present, spoiling the fact that Kendrix's death was only temporary.
Prior to its airing on TV, the Power Rangers Lightspeed Rescue episode "Trakeena's Revenge" was sold in limited McDonald's in April that year, and thus providing spoilers (to those not Sentai educated) for the later portion of the series such as the Rangers' Omega Megazord, Max Solarzord, V-Lancers, Battle Boosters. There's also the first onscreen appearance of Olympius, as well as Queen Bansheera who has partially taken physical form.
Power Rangers Samurai "movie", Clash of the Red Rangers, was recorded along with the second season block of episodes, but aired at the end of the first season. It revealed a number of power ups the Rangers had not achieved yet.
DVD covers of Pretty Little Liars' later seasons depict Alison along with the other four girls, which makes it hard to believe she's actually dead in the first three seasons.
This was unavoidable for Prison Break. People still watching Season 1 when Season 2 began airing were treated not only to the fact that they break out and are on the run from the law, but also who survived/escaped and who didn't by showing the entire team of escapees. Then people watching Season 1 or 2 when Season 3 comes out were greeted with the fact the team are re-captured and put into a new prison.
The trailer for the third episode of Ravenswood spoils the death of Miranda which was a big cliffhanger as which main character would die in the previous episode.
The box set of Robin Hood's season three has "Marian's death was just the beginning" on the back.
Roswell: The summary on the back of the second season's boxed set mentions that Alex dies, which is an out-of-nowhere twist that comes two-thirds of the way through the season.
The season 2 commercials for Sherlock showed who Moriarty was, despite the fact that it was the major plot point in the entire first season.
Back when The Shield was still airing, you couldn't sniff ANY promo material on Season 6 without finding out that (HUGE S5 Spoiler):Curtis "Lem" Lemansky was killed.
The DVD issues of Spartacus:Vengeance spoiled the unexpected reappearances of Lucretia and Gannicus by having the actors' portraits on individual discs.
Beautifully parodied and lampshaded in Stargate SG-1 episode "200". Every ad on Sci-Fi showed Richard Dean Anderson in the episode. When the episode aired and General O'Neill shows up, Samantha Carter says it would be a surprise to which Daniel Jackson responds "Are you kidding, it'll be in the previews."
Star Trek: The Next Generation: Picard plays such a substantial role in seasons 4-7 that it would be almost impossible for someone to get as far as "The Best of Both Worlds" without knowing that he's going to not only survive, but also escape the Borg and reclaim his human identity.
On the Star Trek: Deep Space Nine episode "The Wire", Garak tells several (conflicting) stories about his past as a spy with his friend Elim. The end of the episode reveals that Elim is simply Garak's first name. But you'd be hard pressed to find a reference to Garak, including the Deep Space Nine page on This Very Wiki, that doesn't list him as "Elim Garak", which takes the sting out of the episode.
Promotional materials for later seasons of Supernatural show Bobby in a wheelchair. Also, Dean did go to hell. Viewers who had seen the publicity for later seasons would know that when Raphael smote Cas, it wasn't permanent. Also for viewers watching the fourth season, Sam and Dean are not going to stop all the seals from being broken. And -as the intro re-cap for the early episodes of season five will tell you - Lilith was the final seal.
Watching the series and yet not up to par on your Super Sentai knowledge despite Gokaiger being an anniversary series? Too bad, because the subject matter of episode 28 is the death of Gai Yuuki in Choujin Sentai Jetman, which happens to be the final scene of that series! And even then, it was left sort of ambiguous unless you were a super fan and watched the special Clip Show epilogue or read the manga.
If you hadn't watched Samurai Sentai Shinkenger beforehand and didn't know that Kaoru Shiba was the true Shinken Red, episodes 11 and 12 ensure that you do now.
Gokaiger also spoils the final scene of Mirai Sentai Timeranger, in which Honami reveals that Domon knocked her up. And also that Naoto dies.
Jan's lack of necklace in Juken Sentai Gekiranger is sort of a spoiler for those who notice it missing, considering he does not receive it until the finale. Also the fact that Rio and Mele get Ranger Keys in Gokaiger.
Didn't know that Wolzard does a HeelFace Turn in Mahou Sentai Magiranger? You do now, after Gokaiger's final Ranger Key reveal. The third movie also shows Vancuria in a prison filled with villains who weren't exactly evil.
If you haven't watched the first two series of Torchwood and wonder why in official images and the DVD cover for the third season only Jack, Gwen, and Ianto appear.
If you haven't watched the third series of Torchwood and wonder why in official images and the DVD cover for the fourth season only Jack, Gwen and some new guys appear.
The second-season trailer (which was released months before its official premiere) shows the entire cast hiding from a horde of walkers during a forced stop on a congested highway, and then staring out from the side of the highway afterwards - minus several characters who were present in the first season's advertising campaign. So, if you're wondering where Amy, Jim, Jacqui, Ed and Morales (who left with his family) went, well... the second season premiere goes one further and gives a recap of the previous season's events, with the line, "We lost some people."
During the third season preview weekend/catch-up marathon, they went one step beyond that. Between commercial breaks and the show they talked to the actors about various things, spoiling twists in the current episode (like mentioning the fate of Sophia during the episode where that's revealed at the very end of the episode). There were times where they'd ruin the entire episode after the very first break. They'd also have trailers for the next episode in the marathon that spoiled some of the episode.
The third-season trailer has a Time Skip showing that the group has left the farm and been on the road for months, minus several people (including Shane). It also reveals Michonne's identity, spoiling it for people who would have been surprised by Andrea's rescuer in the final minutes of "Beside The Dying Fire".
The fourth-season trailer spoils that Tyreese and Sasha have joined the prison group, as well as that the residents of Woodbury have also joined with Rick and the other survivors.
From the fifth season onwards, the show got a bit better about not spoiling major plot points (usually resorting to Manipulative Editing to paint a much different picture), but it was still guilty of this. The Comi-Con trailer for Season 5 shows that the entire group has been captured by a bunch of cannibals, as well as the final shot of the previous season (where Rick tells the group that they screwed with the wrong people).
The Comic-Con trailer for the sixth season spoils that Morgan (a minor character who had been absent since the pilot episode, and returned in cameos throughout the fifth season) finally joined Rick and the others in the fifth-season finale, via replaying the final shots of the episode.
Season six ended on a massive Cliffhanger, forcing the trailer editors to work around by showing everything up to the final moments of the previous season. As a result, audiences new to the show know that the entire main cast is at the mercy of a baseball-bat wielding madman, who is picking someone at random from a lineup and beating them to death with his trusty baseball bat.
While the season 2 finale was obviously a cliffhanger when the series first aired, anyone who knows there are seven seasons of The West Wing (which is to say, anyone who has heard of the show) will be utterly unsurprised by President Bartlet a) running for and b) winning re-election.
Like the Buffy example above, Aaron Sorkin was baffled by the fact that people didn't realize that the President was planning to run again.
Plus the "Who's been hit?!" cliffhanger of the first season, which any later season will invalidate (two main characters are shot, but no one dies).
The Season 2 DVD of White Collar holds the massive spoiler that the death of Kate in the first season finale is a major plot thread through out the season.