History Retcon / WesternAnimation

** ''The Simpsons'' FloatingTimeline 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' ages [[NotAllowedToGrowUp 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.

** 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).

* When Morph is revealed to be alive in season 2 of ''WesternAnimation/XMen,'' 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 [[NeverFoundTheBody 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.

** The Season 25 episode "The Big Fix" has a particularly hilarious one. When Randy gets Stan to invite Token's family over to dinner so that he can have a black best friend to improve the image of his weed business, Randy asks what the deal is with Token's name. Only for him and Stan to learn to learn that Token's name is actually ''Tolkien'', as in the [[Creator/JRRTolkien influential fantasy writer]], not TokenMinority. Stan is additionally shocked to learn that {{everybody knew already}}, with all past instances of Tolkien's name being written as "Token" getting handwaved as misspellings. When he directly states what he thought Tolkien's name was to his doctor, the man calls him a terrible person for ever believing such a thing, before [[BreakingTheFourthWall turning to address the audience]] to insult us for ever thinking the same as well.

** In a season two episode, Ozai and Iroh's father Azulon is said to have been Fire Lord for 23 years before Ozai. The Nick website also provided a brief backstory for Sozin saying that he was a young man when he became Fire Lord shortly before Roku died and was prevented from starting the war until the elder Avatar Roku's death, and that Sozin ruled for the first 70 or so years of the 100 year war. Come season three, 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 stated 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, explicitly contradicting what is said in the season two episode.

** In a season two episode, 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 he 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.

** {{Lampshade|Hanging}}d in the 9th season episode "Excellence in Broadcasting": When the Griffins hear that Radio/RushLimbaugh is coming to town to promote his latest book, Chris recalls that, during Lois' brief stint at Creator/{{Fox News|Channel}} (in the "Foxy Lady" episode), she reported that both Limbaugh and Michael Moore were characters played by Creator/FredSavage. Lois [[{{Handwave}} dismisses]] this, explaining that even if something is true to begin with it becomes a lie when said on Fox News.

*** In the Japanese fiction, it was the reformatted corpse of Unicron from an alternate future timeline from the [[ComicBook/TheTransformers Marvel Tranformers comics]] and landed in this universe. Apparently, [[Anime/TransformersCybertron Megatron/Galvatron's absorption of Unicron's power and transformation into Master Megatron]] had caused this body to go into a frenzied repair mode, attempting to sustain itself.
*** [[MindScrew Does your head hurt yet?]]Not only do the retcons only makes things more confusing, but they are also [[VoodooShark contradictory]], as Megatron/Galvatron's imprison and subsequent absorption of Unicron's power took place in year 2013/2014 timeline-wise, but Planet X existed and was destroyed in a war that took place in the ''sixth century''.

* The Season 25 episode "The Big Fix" has a particularly hilarious one. When Randy gets Stan to invite Token's family over to dinner so that he can have a black best friend to improve the image of his weed business, Randy asks what the deal is with Token's name. Only for him and Stan to learn to learn that Token's name is actually ''Tolkien'', as in the [[Creator/JRRTolkien influential fantasy writer]], not TokenMinority. Stan is additionally shocked to learn that {{everybody knew already}}, with all past instances of Tolkien's name being written as "Token" getting handwaved as misspellings by Cartman. When he directly states what he thought Tolkien's name was to his doctor, his doctor calls him a terrible person for ever believing such a thing, before [[BreakingTheFourthWall turning to address the audience]] to insult us for ever thinking the same as well.

** Similarly the first episode implies that the avatar has been missing for a much longer time than is later shown with Iroh telling Zuko that not only had his Father and Grandfather both searched for the Avatar, but his Great Grandfather as well. This great grandfather is never referred to on-screen again and it is later shown that Zuko's grandfather was the one to start the search.

* ''WesternAnimation/ThomasAndFriends'': 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 [[MerchandiseDriven the new character]] ''Hiro'' was responsible for building it. Of note is that Hiro was built in 1931
** [[https://tvtropes.org/pmwiki/pmwiki.php/WesternAnimation/TheAdventureBegins The Adventure Begins]] Re-retcons this, with Edward becoming the first standard gauge engine on Sodor.

** The japanese version of Generation 1 timeline is possibly the most infamous example. It's hard to note every single retcon without a wall of text that triples the page's size, but whats easier to note is the most drastic ones that difers from the western G1 timeline:

*** [[Anime/TransformersRobotsInDisguise Transformers: Robots in Disguise]] (or more specifically, its japanese version "Car Robots") was retroactively implemented to the japanese G1 timeline, despite the fact the show is self-contained and doesn't references existing G1 timeline or material(among several incompatible facts, like how the public seems unaware of Transformers at first despite the fact they were well-known in the G1 cartoon continuity since the early 80s, while the show takes place in the 2000s or why none of the G1 cast ever appears). It even shoehorn a early 2000s unfinished manga/self contained G1 story in to explain why the G1 cast was absent during the timeframe of the show. Meanwhile, in the West it remains a self-contained continuity unrelated to the G1.
*** The [[NoExportForYou japan-only]] Beast wars shows were initially set concurrently with the american ones, with Lio Convoy and the likes hailing from same time period as Primal. However, the anime staff completely contradicted this(whenever on purpose or accident is unclear) and had the cast as decendants from thousands of years after the WesternAnimation/BeastWars cast. Several retcons were needed in order to accomodate this, the biggest one being the discrepacy of Vector Sigma's portrayal and appearance between [[WesternAnimation/BeastMachines Beast Machines]] and [[Anime/BeastWarsNeo Beast Wars Neo]] of Cybertron(it becomes technorganic on the finale of the former, and in the latter, supposedly thousands of years later its back to a fully mechanical world with no explanation), which was explained in a [[https://tfwiki.net/wiki/Legends_Comic:_Bonus_Edition_Vol._EX_(Blue_Big_Convoy) japanese comic]].

*** In the japanese fiction, it was the reformatted corpse of Unicron from an alternate future timeline from the [[ComicBook/TheTransformers Marvel Tranformers comics]] and landed in this universe. Apparently, [[Anime/TransformersCybertron Megatron/Galvatron's absorption of Unicron's power and transformation into Master Megatron]] had caused this body to go into a frenzied repair mode, attempting to sustain itself.

* ''WesternAnimation/ThomasAndFriends'': 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 [[MerchandiseDriven the new character]] ''Hiro'' was responsible for building it.

** In Lethal Inspection, [[spoiler: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.

** Originally when the fairies were shown as babies they looked like miniature diaper clad versions of themselves, but when Poof was introduced it was retconned that all baby fairies look like little round balls with faces, short stubby limbs, tiny wings, and hair.

*** In the japanese fiction, it was the reformatted corpse of Unicron from an alternate future timeline from the [[ComicBook/TheTransformers Marvel Tranformers comics]] and landed in this universe.
Apparently, [[Anime/TransformersCybertron Megatron/Galvatron's absorption of Unicron's power and transformation into Master Megatron]] had caused this body to go into a frenzied repair mode, attempting to sustain itself.
[[MindScrew Does your head hurt yet?]]Not only do the retcons only makes things more confusing, but they are also [[VodooShark contradictory]], as Megatron/Galvatron's imprison and subsequent absorption of Unicron's power took place in year 2013/2014 timeline-wise(Galaxy force apparently takes place in 2014 now, as opposed to 2030 as in Cybertron), but Planet X existed and was destroyed in a war that took place in the "sixth century".

*** In the japanese fiction, it was the reformatted corpse of Unicron from an alternate future timeline from the [[Comic/TheTransformers Marvel Tranformers comics]] and landed in this universe.

*** The [[NoExportForYou japan-only]] Beast wars shows were initially set concurrently with the american ones, with Lio Convoy and the likes hailing from same time period as Primal. However, the anime staff completely contradicted this(whenever on purpose or accident is unclear) and had the cast as decendants from thousands of years after the WesternAnimation/BeastWars cast. Several retcons were needed in order to accomodate this, the biggest one being the discrepacy of Vector Sigma's portrayal and appearance between [[WesternAnimation/BeastMachines Beast Machines]]and [[Anime/BeastWarsNeo Beast Wars Neo]] of Cybertron(it becomes technorganic on the finale of the former, and in the latter, supposedly thousands of years later its back to a fully mechanical world with no explanation), which was explained in a [[https://tfwiki.net/wiki/Legends_Comic:_Bonus_Edition_Vol._EX_(Blue_Big_Convoy) japanese comic]].

*** The [[NoExportForYou japan-only]] Beast wars shows were initially set concurrently with the american ones, with Lio Convoy and the likes hailing from same time period as Primal. However, the anime staff completely contradicted this(whenever on purpose or accident is unclear) and had the cast as decendants from thousands of years after the WesternAnimation/BeastWars transpired. Several retcons were needed in order to accomodate this, the biggest one being the discrepacy of Vector Sigma's portrayal and appearance between [[WesternAnimation/BeastMachines Beast Machines]]and [[Anime/BeastWarsNeo Beast Wars Neo]] of Cybertron(it becomes technorganic on the finale of the former, and in the latter, supposedly thousands of years later its back to a fully mechanical world with no explanation), which was explained in a [[https://tfwiki.net/wiki/Legends_Comic:_Bonus_Edition_Vol._EX_(Blue_Big_Convoy) japanese comic]].

*** The [[NoExportForYou japan-only]] Beast wars shows were initially set concurrently with the american ones, with Lio Convoy and the likes hailing from same time period as Primal. However, the anime staff completely contradicted this(whenever on purpose or accident is unclear) and had the cast as decendants from thousands of years after the WesternAnimation/BeastWars transpired. Several retcons were needed in order to accomodate this, the biggest one being the discrepacy of Vector Sigma's portrayal and appearance between [[WesternAnimation/BeastMachines Beast Machines]]and [[Anime/BeastWarsNeo Beast Wars Neo]] of Cybertron(it becomes technorganic on the finale of the former, and in the latter, supposedly thousands of years later its back to a fully mechanical word with no explanation), which was explained in a [[https://tfwiki.net/wiki/Legends_Comic:_Bonus_Edition_Vol._EX_(Blue_Big_Convoy) japanese comic]].

* ''[[Franchise/Transformers Transformers]]'' quite a few across the franchise:

* ''WesternAnimation/Transformers'' quite a few across the franchise:

*** Anime/TransformersRobotsInDisguise (or more specifically, its japanese version "Car Robots") was retroactively implemented to the japanese G1 timeline, despite the fact the show is self-contained and doesn't references existing G1 timeline or material(among several incompatible facts, like how the public seems unaware of Transformers at first despite the fact they were well-known in the G1 cartoon continuity since the early 80s, while the show takes place in the 2000s or why none of the G1 cast ever appears). It even shoehorn a unfinished manga/self contained G1 story in to explain why the G1 cast was absent during the timeframe of the show. Meanwhile, in the West it remains a self-contained continuity unrelated to the G1.

* ''WesternAnimation/ThomasTheTankEngine'': 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 [[MerchandiseDriven the new character]] ''Hiro'' was responsible for building it.