History Main / ImposterForgotOneDetail

* In ''Fanfic/TheWitchOfTheEverfree'' side story ''Don't Invite Witches to Weddings'', Sunset Shimmerseemingly falls for Queen Chrysalis' Cadance disguise... only for the unicorn to bluntly reveal that her magic color was wrong. Chrysalis has an acidic green aura, Cadance's is an icy shade of blue. Cut to Chrysalis bursting into Celestia's office in a panic, [[KnowWhenToFoldEm chucking a still bound-and-gagged Cadance at her hooves]], [[AintTooProudToBeg begging for sanctuary]] from Sunset's wrath, and then [[ScrewThisImOuttaHere self-]][[SuperWindowJump defenestrating]] when she doesn't get it. The whole thing is PlayedForLaughs.

* In ''Fanfic/TheWitchOfTheEverfree'' side story ''Don't Invite Witches to Weddings'', Sunset seemingly falls for Queen Chrysalis' Cadance disguise... only for the unicorn to bluntly reveal that her magic color was wrong. Chrysalis has an acidic green aura, Cadance's is an icy shade of blue. Cut to Chrysalis bursting into Celestia's office in a panic, [[KnowWhenToFoldEm chucking a still bound-and-gagged Cadance at her hooves]], [[AintTooProudToBeg begging for sanctuary]] from Sunset's wrath, and then [[ScrewThisImOuttaHere self-]][[SuperWindowJump defenestrating]] when she doesn't get it. The whole thing is PlayedForLaughs.

* In the Fanfic/TheWitchOfTheEverfree side story ''Don't Invite Witches to Weddings'', Sunset seemingly falls for Queen Chrysalis' Cadance disguise... only for the unicorn to bluntly reveal that her magic color was wrong. Chrysalis has an acidic green aura, Cadance's is an icy shade of blue. Cut to Chrysalis bursting into Celestia's office in a panic, [[KnowWhenToFoldEm chucking a still bound-and-gagged Cadance at her hooves]], [[AintTooProudToBeg begging for sanctuary]] from Sunset's wrath, and then [[ScrewThisImOuttaHere self-]][[SuperWindowJump defenestrating]] when she doesn't get it. The whole thing is PlayedForLaughs.

* In the Fanfic/TheWitchOfTheEverfree side story ''Don't Invite Witches to Weddings'', Sunset seemingly falls for Queen Chrysalis' Cadance disguise... only for the unicorn to bluntly reveal that her magic color was wrong. Chrysalis has an emerald green aura, Cadance's is an icy shade of blue. Cut to Chrysalis bursting into Celestia's office in a panic, [[KnowWhenToFoldEm chucking a still bound-and-gagged Cadance at her hooves]], [[AintTooProudToBeg begging for sanctuary]] from Sunset's wrath, and then [[ScrewThisImOuttaHere self-]][[SuperWindowJump defenestrating]] when she doesn't get it. The whole thing is PlayedForLaughs.

* In the Fanfic/TheWitchOfTheEverfree side story ''Don't Invite Witches to Weddings'', Sunset seemingly falls for Queen Chrysalis' Cadance disguise... only for the unicorn to bluntly reveal that her magic color was wrong. Chrysalis has an emerald green aura, Cadance's is an icy shade of blue. Cut to Chrysalis bursting into Celestia's office in a panic, [[KnowWhenToFoldEm chucking a still bound-and-gagged Cadance at her hooves]], [[AintTooProudToBeg begging for sanctuary]] from Sunset's wrath, and then [[ScrewThisImOuttaHere self-]][[DestinationDefenestration defenestrating]] when she doesn't get it. The whole thing is PlayedForLaughs.

* ''VideoGame/{{Arknights}}'': In Episode 10, [[spoiler:the Damazti Cluster]] disguised themselves as a member of the LaResistance to infiltrate the group and mark them for destruction by Manfred's forces. They eventually got discovered due to not knowing that the man they disguised themselves as [[spoiler:adored metal crabs and previously asked for one]], dismissing one that was found to give to the man as "worthless".

* ''WesternAnimation/WinxClub'': In [[Recap/WinxClubS1E5DateWithDisaster "Date with Disaster"]], the first hind is "Stella's" strange behaviour while looking for her ring. In addition to that, Bloom is able to tell that it's actually Darcy in disguise as she uses magic, despite Stella (at her current fairy level, at least) not being able to use magic without her ring.

* ''WesternAnimation/WinxClub'': In [[Recap/WinxClubS1E5DateWithDisaster "Date with Disaster"]],
the first hind is "Stella's" strange behaviour while looking for her ring. In addition to that, Bloom is able to tell that it's actually Darcy in disguise as she uses magic, despite Stella (at her current fairy level, at least) not being able to use magic without her ring.

** One famous test for German spies infiltrating American camps during World War Two was asking the name of Mickey Mouse's girlfriend (Minnie, of course!).
** Another WWII example provided a surprise inversion of the trope. Americans testing for infiltrators would say the phrase "The terror of flight". Anyone who responded "The gloom of the grave" was immediately outed as a spy. Why? Those lines come from the third verse of "The Star-Spangled Banner", the national anthem of the United States. American higher-ups realized that German spies would practice their false identities by memorizing the entire anthem...an example of ''over''-preparing, as very few Americans would know the whole song by heart (many Americans don't even realize that "The Star-Spangled Banner" has multiple verses to begin with). So, in this case, the impostors ''remembered'' too many details.
* During World War 2, any attempt by the Germans to pass forged documents to the Soviets ended up being exposed. The fakes were recognized even by ordinary soldiers. After a long time, it became a well-known secret. Paper clips in the Soviet Union were made of ordinary steel (and in wartime, they rusted), and German paper clips (including the forgery of Soviet documents) used stainless steel.

* ''Anime/BakuganBattleBrawlers'' has shapeshifter Zennet using her EasyImpersonation skills to transform into [[TheChick Julie]]. Dan sees through her when she acts like an EntitledToHaveYou bitch.

* In the original ''Fanfic/{{Shadowchasers}}'', Jinx is looking for the shapeshifting boggart in a wax museum (an ''incredibly'' dangerous situation, like looking for a needle in a haystack and the needle is trying to kill you). However, when she passes by a display representing the duel between Obi-Wan and Darth Vader in ''Film/ANewHope'', she notices that the Darth Vader statue has a ''green'' lightsaber, and realizes ''that'' must be him.

* Subverted in the 1977 version of ''Film/TheManInTheIronMask''. Minister Fouquet is confronted with King Louis and his identical twin dressed exactly the same, except his sash is the wrong color (a detail the conspirators changed so they'd know who their man was) so Fouquet has him arrested. He's the twist--the conspirators knew Fouquet was on to them, so arranged for him to be told earlier that the king had changed his mind about the color of his sash. Fouquet has actually arrested the real king.

* ''Literature/TheSandman1989'': The monk immediately clocks that these warriors trying to intimidate them are the work of a badger, because while the magick is otherwise spotless, the last horse's tail is that of a badger. He's right.

* "Ghost World," an episode of ''WesternAnimation/TheRealGhostbusters'', saw the entire team except Egon being captured and possessed by ghosts. Egon, sensing something is wrong, asks Janine how her sister is doing; when she responds positively, he immediately goes for his ghost-hunting equipment, as Janine doesn't ''have'' a sister.

* ''WesternAnimation/ArabianKnights'': In "The Spy", Zazum is accidentally separated from the Knights during a confrontation with Bakar's guards. A ShapeShifter in Bakar's army transforms into Zazum so as to infiltrate the Knights' home base. Unfortunately, he didn't learn the habits of "the real beast": when offered hay and an apple, he refuses both. Furthermore, when his tail is pulled, he doesn't bray and go into his tornado spin. Nida doesn't have this issue when she impersonates the changeling.

* Near the end of ''VideoGame/MinionQuestTheSearchForBowser'' [[spoiler: "Bowser" tells Captain Goomba to destroy Mario, who is on his way to Bowser's Castle. Goomba seems confused about it at first (since Bowser would never say such a thing), but agrees anyway. Sure enough, "Bowser" is Cackletta [[GrandTheftMe possessing Bowser as Bowletta]] on a plan of [[TheDragon Fawful]] in hopes the Koopa Troop and the Mario Brothers would destroy each other.]]

** In another episode, Goliath is captured by an evil shapeshifter, and when Eliza and her allies go to rescue him, the creature assumes her form, forcing the heroes into a SpotTheImpostor scenario. Goliath then calls out a question -- "Eliza, tell me truth! Was there ever a time, even for a moment, that you doubted me?" One Eliza promptly responds "Never!" -- and ''that's'' the one Goliath names as the fake. The monster couldn't have known that Eliza and Goliath's relationship is brimming with doubt, especially since ''he'' was responsible for the rift between them at the start of the episode.

* In ''Literature/TheFourthProtocol'', the head of the British SIS Sir Nigel Irvine identifies a Soviet double agent posing as an Afrikaner diplomat and running a FalseFlag operation to get mid level bureaucrats with sympathies to South Africa to give up secrets to him. Irvine finds old photographs of the diplomat playing cricket at university and notices that he’d played as a left arm spinner. But the man claiming to be the diplomat is right handed[[note]]It is actually possible for people who are naturally right handed to still bowl and/or bat left handed. Famous examples being Indian all rounder Ravi Shastri who bowled left arm spin but batted right handed.[[/note]]. Irvine eventually outs the diplomat as a German communist agent who [[KillAndReplace had killed and assumed the identity of]] the Afrikaner long ago.