History Main / SpannerInTheWorks

* Nicely played with in ''Film/QuickChange''. Grimm has carefully planned out a complex New York City bank robbery and it goes off without a hitch. He correctly anticipated just how the cops would react, how the hostages would behave and the exit strategy perfect. Grimm is just as confident the trio's plan to get through airport security and flee the country will also work. Sadly, Grimm never considers that ''getting to'' the airport is going to turn into a disaster...
** The first problem is Grimm not knowing that the signs to a key expressway were removed during construction, leading to the trio getting lost in Brooklyn. From there, they're robbed themselves, a fire truck pushes their escape van down a hill, they run afoul of a mafioso and it just gets worse after that point. [[spoiler: Amazingly, they do manage to escape but it's more sheer blind luck than anything they could have planned for]].

** Larry Butz also counts, owing to his tendency to do unreasonable things that end with him [[LuckBasedSearchTechnique stumbling onto vital evidence]]. In the first game, he [[spoiler: was coincidentally returning a boat he had been using at precisely the right time to overhear a gunshot]], in the third he [[spoiler: shirked his work as a security guard when the villain's plan relied on him being at his post so that he would hear the noise of a panic button, rush into the room and arrest the wrong person]] and then in a later case his choice to [[spoiler:wander around at night in the cold]] leads to him witnessing a number of things he wasn't meant to. Lampshaded in the fourth case of the first game, when Edgeworth remarks that this is the first time von Karma has had to deal with a witness he hasn't questioned in advance, which gives them the opportunity they need to find the truth.

* Boomer, a MadBomber from the Wiki/SCPFoundation storyline "Game Day", tends to carelessly leave dangerous explosives in random places around his hideout, to the point that it's not really possible to plan a safe approach to it.

** ''VisualNovel/PhoenixWrightAceAttorneyDualDestinies'' sees Phineas Filch end up as one in the second case. [[spoiler:Florent L'Belle's entire scheme -- a plot which took months of planning, backstabbing, manipulation, blackmail, threats, and outright murder, one so complicated that it's lampshaded how [[ComplexityAddiction insanely complicated it all is]] by Apollo Justice -- was all to have unrestricted access to the Forbidden Chamber in Nine-Tails Vale to steal a gold ingot supposedly contained inside of the Chamber. Filch, on the other hand, snuck into the Forbidden Chamber on a whim in fifteen minutes because he was bored. By doing so, Filch spooked Jinxie Tenma, which forced L'Belle to improvise a few things, proving to be his downfall in court.]]

->''"A common mistake people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools."''
-->-- '''Creator/DouglasAdams''', ''Literature/MostlyHarmless''

* In ''Film/TheAtomicBrain'', as shown on the TV series ''Series/MysteryScienceTheater3000'', in spades. The main plot for the villain Miss Marsh was for her to have her brain swapped with the prettiest girl of three chosen. That gets ruined when the homeliest of the three, who had her brain swapped with the cat's, [[EyeScream gouges her eye out]]. Miss Marsh's companion tries to double-cross her, killing her and letting the remaining girl take her money, but Marsh kills him. The scientist, Dr. Otto Frank, pulls one by placing Miss Marsh's brain with the cat's, revealing that he wanted to keep her locked away in the cat so he could use her money to continue his research on reviving the dead. Miss March responds by locking him in the revival chamber and setting the dial to "Frag the entire house".
* ''Film/{{The Avengers|2012}}'':
** Had Thor not been there to keep the Hulk at bay the Helicarrier would have crashed and Loki's plan would have more than likely been successful.

* ''Machinima/RedVsBlue'':

* ''Film/ForrestGump'' calls to complain that he can't sleep because of people playing with flashlights in the next building over, and so [[HistoricalInJoke blows the lid on Watergate]].

** Believe it or not, Valorum is this since before the films even chronologically began. Despite him being an ineffective leader, he was still a man with good intentions, and when the Senate didn't listen to him for too long, he decided to send the Jedi to negotiate with the Trade Federation without consulting with the senate, thus unwittingly planting the seeds for Palpatine's downfall.

* Sakura Ogami also manages this. In the fourth chapter, she [[spoiler: commits suicide, but before she did this she broke the lock on the Headmaster's Office (breaking down doors was against school rules, so no student who wanted to live would do it- but since Sakura was ''already'' planning to kill herself, she broke it without fear) to get posthumous revenge on Monokuma. Not only does her suicide help Makoto rally the students against Monokuma, the Headmaster's office being open allows Kyoko to grab Mukuro Ikusaba's student profile and a master key that allowed her to access ''every'' room in the school, which ultimately leads to the Mastermind's unmasking.]]

** Case 2-2 has Maya's little cousin, Pearl, who manages to undermine the real killer's alibi and retrieve important evidence simply by running around doing kid stuff.

** The whole reason Phoenix gets involved in ''Justice for All'''s forth case is that Adrien Andrews was the first on the scene of the crime and rearranged it to frame Matt Engarde.[[spoiler: Matt had hired Shelly de Killer to murder the victim. Shelly prides himself on professionalism and protecting his client (and himself had left no evidence that could directly trace back to Matt), so when Matt is arrested anyway (thanks to Adrien FramingTheGuiltyParty), he kidnaps Maya to force Phoenix to take the case and get Matt aquited. This leads to the complete mess that is case 2-4, but it also means that Phoenix finds evidence that Matt actually ''was'' guilty (and, more importantly, that he'd planned on betraying de Killer), something that never would have happened if de Killer had simply killed the victim and got away like he'd planned.]]

** In the fourth case of ''Justice For All'', the lead that helps Gumshoe and company track down Shelly de Killer is, of all things living and not living, [[spoiler:Matt Engarde's ''cat'', who meows at the end of a transmission from de Killer]].

** Larry Butz also counts, owing to his tendency to do unreasonable things that end with him [[LuckBasedSearchTechnique stumbling onto vital evidence]]. In the first game, he [[spoiler:was coincidentally returning a boat he had been using at precisely the right time to overhear a gunshot]], in the third he [[spoiler:shirked his work as a security guard when the villain's plan relied on him being at his post so that he would hear the noise of a panic button, rush into the room and arrest the wrong person]] and then in a later case his choice to [[spoiler:wander around at night in the cold]] leads to him witnessing a number of things he wasn't meant to. Lampshaded in the fourth case of the first game, when Edgeworth remarks that this is the first time von Karma has had to deal with a witness he hasn't questioned in advance, which gives them the opportunity they need to find the truth.

** In ''Trials and Tribulations'', Furio Tigre's plan to use Glen Elg's [[spoiler:MC Bomber virus, worth several million dollars, to pay off his own million-dollar debt was annihilated because the moment the exchange was about to happen, Elg miraculously [[NeverWinTheLottery wins half a million in the lottery]]]].

* ''Film/{{Goosebumps}}'': Usually whenever one of the Goosebumps manuscripts is unlocked and a monster escapes, Stine manages to capture it and he and his daughter are forced to move. When Zach releases the Abominable Snowman, however, the bookcase collapses and Slappy escapes as well. Slappy then proceeds to release every monster R.L. Stine ever created and burns the manuscripts for good measure.

* In ''[[Film/{{Oceans 11}} Ocean's 11]]'', all it takes is [[spoiler:Anthony Burgdorf's widow deciding to have his funeral in Las Vegas]] for Operation [[spoiler:Pine Box]] to go to hell.

** Larry Butz also counts, owing to his tendency to do unreasonable things that end with him [[LuckBasedSearchTechnique stumbling onto vital evidence]]. In the first game, he [[spoiler:was coincidentally returning a boat he had been using at precisely the right time to overhear a gunshot]], in the third he [[spoiler:shirked his work as a security guard when the villain's plan relied on him being at his post so that he would hear the noise of a panic button, rush into the room and arrest the wrong person]] and then in a later case his choice to [[spoiler:wander around at night in the cold]] leads to him [[HeKnowsTooMuch witnessing a number of things he wasn't meant to]].

** In the final case of ''VisualNovel/AceAttorneyInvestigations'', the shenanigans of [[spoiler: Larry Butz and Wendy Oldbag, of all people]] end up helping Miles Edgeworth put away the seemingly untouchable BigBad. [[spoiler:Larry, by accidentally breaking the Samurai Spear, forces the staff to have the Steel Samurai use a different move instead, thus enabling Edgeworth to realize that Alba was not at the Steel Samurai show while he was killing Manny Coachen. Wendy Oldbag takes the box of "Rising Sun Dogs" thinking they were some sort of limited edition Samurai Dogs, when they were actually a perfectly normal box of Samurai Dogs with a drop of Alba's blood on it, and combined with Alba's wound, proves that he was injured while killing Coachen]].

** In ''VisualNovel/DanganronpaTriggerHappyHavoc'', the entire triumph of hope over despair on Earth hinges on a poorly-fitting bathroom door that gets stuck in the doorframe. A door which, because of Naegi's Ultimate-level luck (which manifests as [[UnluckilyLucky seemingly-bad luck that turns out to be good luck in disguise]]), gives him an alibi for a crime he would otherwise have been framed and executed for. [[MessianicArchetype Given how important Naegi would go on to be to the future of humanity]], it's no exaggeration to say that ''that'' was the moment that the mastermind's fate was well and truly sealed. Even worse, it's implied that the mastermind deliberately ''gave'' him the crappy door just because [[ItAmusedMe they thought the idea of the Ultimate Lucky Student being the only one with a crappy door was funny]].

** In the game's first case, the murder's plot is more or less derailed by the fact that Aoi happens to be sitting in the dining hall at a certain time, and as a result realizes that there's only one person who could've possibly could've retrieved the murder weapon from the kitchen. Sure, [[spoiler: the murder's plot ended up backfiring and getting them killed by their intended victim]], but that particular piece of evidence is integral in figuring out what really happened and identifying the killer.

*** Also invoked ad verbatim in the second game's third case by [[spoiler:the engineer Enoch Drebber.]] The plan involved [[spoiler:destroying his room with a time bomb set in plain sight, while he's concealed inside an impenetrable safe: should anyone happen to enter the room, they would normally run away in panic. The room would blow up with no one else in it, and thus the bomb would dispose of vital evidence while simultaneously hiding Drebber's presence]]. This entire scheme backfires when, upon the police's arrival at the scene, [[GreatDetective Great Detective]] Herlock Sholmes instead [[spoiler:mistakes it for an antigravity device]] and spends several minutes performing a complex deduction with the help of Naruhodo[[spoiler: to locate Drebber within the room, risking their lives but also completely foiling Drebber's plan]].

** When the Order [[https://www.giantitp.com/comics/oots1224.html planned an ambush]] [[spoiler:for Xykon, they end up getting derailed by Serini, who believed that it was for the best to prevent them from stopping Xykon. By the time the Order convinces her otherwise, [[https://www.giantitp.com/comics/oots1257.html they are informed by Blackwing that Xykon has come out and they've missed their window of opportunity]], cause Roy to actually lose his cool and go into a ClusterFBomb]].

* ''WesternAnimation/TheLionKing'': Timon and Pumbaa inadvertently save Simba while scaring off buzzards, and raise him into his adult years. Without them, Simba would've likely died in the desert and Scar would've driven the Pride Lands further into irreparable doom.

* In ''WesternAnimation/{{Home}}'', Pig the cat's presence spare Tip from being abducted with the rest of the humans. When the Boov are collecting the humans, Pig panics and clings to Tip's head. The scanner detects Pig instead of Tip and disregards them both, causing Lucy to be taken alone. [[spoiler:Were it not for this twist of fate, Earth and the Boov would likely have been destroyed]].
* ''WesternAnimation/TheLittleMermaid'': Scuttle is the recurrent reason Ursula's con on Ariel fails and the film doesn't have the same DownerEnding as the original fairy tale. Not only does he catch Ursula gloating about her plan in her disguise and warn Ariel she has been duped, he arranges the other ocean creatures to stall her wedding with Eric, as well as smashing Ursula's conch to grant Ariel back her voice and break Eric from his hypnotic state so he could pull a BigDamnHeroes.

** In the third case of ''Justice For All'', [[spoiler:Acro's plan to murder Regina was to call her to a specific point where he would drop a heavy weight on her head. Problem is, the note he secretly planted on Regina began with "To the murderer...". Due to Regina being very naive, she didn't think the note was for her, and posted it on the circus's bulletin board, where her father saw it and responded to it in Regina's place]]. Then you realize that [[spoiler:Acro wanted to kill her ''because'' her naivete led to his brother being put into a coma, [[WhatAnIdiot so he really should have known that she would never realize the note was meant for her]]..]].