History Main / SpottingTheThread

* ''{{The Grim Adventures of Billy and Mandy}}'': Nergal Jr. tries to impersonate Mandy, but Billy can tell it's off because she was smiling. Weird use of this trope, as Nergal Jr. keeps his distinct glasses even when disguised as others.

* In ''CodeLyoko'' episode "Franz Hopper", a Polymorphic Clone impersonates Franz Hopper to lure the heroes into a trap. Jérémie realizes he must be an imposter after the fake Franz mention the destruction of his video diary (which occurred in a previous episode) -- something that the real Franz Hopper couldn't have known about, but that XANA certainly did.

!!Examples

* The 2003 remake of TheItalianJob has this: Steve realizes Stella is John's daughter because of a phrase she uses, that he's never heard from anyone one else but John.

* In TheBookOfTheNewSun, Severian spots a ''literal'' thread: [[spoiler:a ribbon sticking out from the side of the head of the mysterious soldier he battles at the Sanguinary Fields, which tips him off that it's really Agilus in disguise.]]
* In DoubleStar by RobertHeinlein, an actor is hired to double for a prominent politician who has been kidnapped, and spends weeks studying files on everyone around him to make the masquerade work. He notices that the file on the emperor is nearly empty, and assumes that they don't have much contact...until he meets the emperor, and gets found out, because why would you need files to remember how you deal with the emperor?

* The AceAttorney games have a ''lot'' of these, such as [[spoiler:Quercus Alba mentioning the name of a finishing move that was never actually used in the stage show he allegedly watched]] in ''Investigations''.
* In TheForceUnleashed 2, [[spoiler: Starkiller realizes that a droid is impersonating Juno Eclipse because the real Juno had been shot in the shoulder earlier.]]

** Metal Gear Solid 2 featured Plissken, who said "Semper Fi", which gave him away as not being Army.

* The 2003 remake of TheItalianJob has this: Steve realizes Stella is John's daughter because of a phrase she uses, that he's never heard from anyane one else but John.

** Also, there's a story about the exchanging passwords, where the guard would call, "Oh say can you see," and expect the answer, "by the dawn's early light?" Then the guard would call, "And where is that band," and if the answer was "who so vauntingly swore,", they'd know it was a spy. Because while any red blooded American could be counted on to know the first verse of the Star Spangled Banner, only a spy who was trying too hard would have memorized the ''third''.

* Many a German spy was outed in World War II for failing to comprehend the mind-numbingly complicated British Imperial monetary system. Until 1971, the complex coinage, nonsensical divisions of currency (240 pennies to a pound...originally because 240 pennies weighed one pound, quarters of pennies, etc.), and the numerous slang terms for the various denominations meant that merely counting change was extremely difficult for foreigners.

* In the Batman crossover ''No Man's Land'', Gotham City is hit with a cataclysmic Earthquake and quarantined. Batman is in the city trying to clean it up, having sent Superman away. But Superman has come back as Clark Kent, trying to help people on a different scale. He tells Batman that he did his best to rough up his clothes so as not to stand out and asks Batman how he did. Batman looks him over and says "The toes of your shoes are scuffed, but you forgot to scuff the heels. Your shirt is dirty but bears no evidence of sweat or epidermal oil secretion stains. And no one around here has smelled of deodorant soap and laundry detergent for over five months." Clark asks how he looks to someone who isn't the world's greatest detective. Batman says he looks fine.

You think you're so smart, don't you? You thought you had the perfect disguise but you forgot one little thing. [[SomethingTheyWouldNeverSay She never calls me by my first name]], [[IAmNotLeftHanded she isn't left handed]], and [[BluffTheImpostor she would never call herself that]].

This is when an impostor will be impersonating someone and have an almost perfect disguise. But it gets ruined by a seemingly inconspicuous mistake that reveals to the person they are trying to fool that they are dealing with an impostor. The paragraph above, while it does have more than one small mistake being made, shows the kinds of mistakes that the impostor may have made.

Can be a sub-trope of SpotTheImpostor except that the character generally has no advance knowledge that there is an impostor in the first place. Related to PullTheThread as this is often what leads to it. Compare INeverSaidItWasPoison. See also ConvictionByCounterfactualClue, when this gets even more unrealistic. When applied to a dream test, it's AGlitchInTheMatrix.

http://static.tvtropes.org/pmwiki/pub/images/fire-extinguisher.jpg
[[caption-width:600:[-Move along, nothing to see here. Hey, wait a minute...-] ]]

* The AceAttorney games have a ''lot'' of these. This Troper's personal favorite is [[spoiler:Quercus Alba mentioning the name of a finishing move that was never actually used in the stage show he allegedly watched]] in ''Investigations''.[[/folder]]

* There is a story of a British spy in occupied France during WWII who was exposed after ordering "Café noir". A local would have known that, with milk being scarce, the "noir" was redundant as that is all there was on offer.
** [[@/{{Bisected8}} This]] (English speaking, with French as a second language) troper would like to point out that as far as he knows, it's actually the case that black coffee is the default in France, (so you would say "café au lait" to ask for coffee with milk rather than the other way around) rather than anything to do with shortages.

* This troper has also read of British spies nearly getting caught for putting spoonfuls of soup straight into their mouthes (in parts of France at the time it was customary for women to sip from the side of the spoon) and, of course, forgetting that the French drive on the right side of the road.

* Shapeshifting fae Nutmeg from ''{{DMFA}}'' pretends to be her husband, but Mab notices it because she didn't get the mannerism and hoof patterns right. Earlier, Jyrras uses a MagiTek patch to pretend to be a cubi, but the disguise is pretty transparent to any real cubi (who are mind readers).

* In [[RobertHeinlein]]'s DoubleStar, an actor is hired to double for a prominent politician who has been kidnapped, and spends weeks studying files on everyone around him to make the masquerade work. He notices that the file on the emperor is nearly empty, and assumes that they don't have much contact...until he meets the emperor, and gets found out, because why would you need files to remember how you deal with the emperor?

* In a Russian fantasy novel ''Wolfhound'' the titular hero exposes a disguised assasin when he noticies that although the man wears a distinct native costume, the patterns on his shirt and boots do not match and indicate him as a member of two different clans at the same time.