History Main / ChekhovsBoomerang

* ''ComicBook/GreenLantern'': Alan Moore once wrote a story prophesying the end of the Green Lantern Corps. Fast-forward a decade or two, and it's become the basis for the ''ComicBook/BlackestNight'' event. Even earlier, the "Blackest Night" Prophecy was also used in the early 1990's when the Green Lantern Corps was destroyed for the first time, when Parallax possessed Hal Jordan. "Blackest Night" was also the title of one of the comics leading to the end of that same arc, implying that Parallax caused the Blackest Night.
* In ''ComicBook/SonicTheHedgehogArchieComics'', Dr. Eggman uses the blue Chaos Emerald to initiate a CosmicRetcon, turning Mobius into its video game counterpart. Sonic fixes this a few issues later, going Super and shunting things back to normal, but the Chaos Emerald disappeared. Two years later, and it's shunted into the ''ComicBook/MegaManArchieComics'' universe, setting the stage for [[ComicBook/SonicTheHedgehogMegaManWorldsCollide the two franchises' crossover]].
* ''ComicBook/XMen'': Gambit falls somewhere between this and ForgottenPhlebotinum. One of his powers is the ability to charm or hypnotize people simply by talking to them. Despite there being a countless number of times this ability would be really helpful, it's typically seen once every few years. However, he ''does'' still use it, so it's not completely forgotten.

* The explosive gum and camera glasses in ''Film/MissionImpossible''. Both introduced at the start among the new gadgets for the mission. The glasses get used to show Jim being shot. The gum is used by Ethan to escape Kittridge. Both are re-used by Ethan in the climax. the glasses to show Kittridge that Jim is TheMole, and the gum is used to take out the helicopter with Kruger and Jim.

* Used several times throughout ''WebVideo/StampysLovelyWorld'', but most notably, the You Again Cloning Contraption, which manages to be a plot device for over ''seven'' years. It was first used in Episode 179, "Cloning Contraption", to clone another Stampy Cat to [[MundaneUtility help with the building]] of the Soggy Sandwich restaurant. Then it's used again in Episode 184, "Clone Calamity", where [[spoiler:the BigBad,[[MesACrowd HitTheTarget]], makes a CloneArmy and [[CloningGambit attacks]] Stampy and Lee using it, and Lee also clones himself to help with the fighting. All the known clones at the time died in the episode, and Stampy breaks the button which would enable the machine to work, though it's replaced at a later point in time]]. Later in Episode 356, "William Beaver", the new Helper, William got curious and decided to clone himself with the machine, once again to help with construction. Finally, [[spoiler:in Episode 700, "Tragic Day", [=HitTheTarget=] and Veeva Dash (HTT's eventual partner-in-crime) recycle their past plan and decide to clone an army of dogs large enough to ZergRush Stampy and his own wolf pack, which proved to be disastrous on both sides, considering that the villainous duo ''still lost the battle'' and two of Stampy's own dogs died in the crossfire (and one more was [[ReportsOfMyDeathWereGreatlyExaggerated mistaken for dead]]), which prompted Stampy to destroy the machine once and for all]].

* Used several times throughout ''WebVideo/StampysLovelyWorld'', but most notably, the You Again Cloning Contraption, which manages to be a plot device for over ''seven'' years. It was first used in Episode 179, "Cloning Contraption", to clone another Stampy Cat to [[MundaneUtility help with the building]] of the Soggy Sandwich restaurant. Then it's used again in Episode 184, "Clone Calamity", where [[spoiler:[[MesACrowd HitTheTarget]] makes a CloneArmy and [[CloningGambit attacks]] Stampy and Lee using it, and Lee also clones himself to help with the fighting. All the known clones at the time died in the episode, and Stampy breaks the button which would enable the machine to work]]. Later in Episode 356, "William Beaver", the new Helper, William got curious and decided to clone himself with the machine, once again to help with construction. Finally, [[spoiler:in Episode 700, "Tragic Day", [=HitTheTarget=] and Veeva Dash (HTT's eventual partner-in-crime) recycle their past plan and decide to clone an army of dogs large enough to ZergRush Stampy and his own wolf pack, which proved to be disastrous on both sides, considering that the villainous duo ''still lost the battle'' and two of Stampy's own dogs died in the crossfire (and one more was mistaken for dead), which prompted Stampy to destroy the machine once and for all]].

* ''Manga/JoJosBizarreAdventureDiamondIsUnbreakable'': In Morioh, there's a cursed alley that a person must never turn around when exiting so they won't be DraggedOffToHell. The heroes use this alley to their advantage twice. First was Rohan using it to remove only the parasitic Stand Cheap Tricks (who attaches itself to Rohan's back and only turn its head when someone looks at Rohan's back), then by Reimi [[spoiler:to finish off the spirit of her murderer [[BigBad Yoshikage Kira]]]].

* ''VideoGame/TheDig'' has a shovel serve as the puzzle solution 10 separate times. At one point the main character even [[LampshadeHanging comments]], "What if I hadn't brought this shovel along? No, that's not worth thinking about."

** In [[Literature/HarryPotterAndTheDeathlyHallows Deathly Hallows]], remember the passage early in the book where [[PlotPoint Scrimgeour denies Harry its ownership, claiming the sword presents itself to any worthy Gryffindor?]] Admit it, you probably forgot about it by the time Griphook got hold of the sword, taking it away from the plot. [[spoiler:And then, as the story is reaching its climax and the sword itself is long forgotten, Neville draws it from the flaming Sorting Hat and beheads Nagini with it, destroying Voldemort's last Horcrux and earning his personal SugarWiki/MomentOfAwesome by the way]]. Now that's a Chekhov's Boomerang!

** The hoverboard in the ''Film/BackToTheFuture'' sequels. At the end of ''[[Film/BackToTheFuture Part II]]'', Marty uses a hoverboard he brought back from 2015 to get back [[TimelineALteringMacGuffin Gray's Sports Almanac]]. He uses the hoverboard again at the end of ''[[Film/BackToTheFuture Part III]]''.
** Lightning being enough to qualify for the 1.21 gigawatts. Obviously important in the [[Film/BackToTheFuture first film]], then it works again ''accidentally'' in the second.

** An example of good game design theory. [[spoiler:The earlier uses of the incinerator and rocket launcher teach the player, setting up for their combined use in the boss fight.]]
*** In fact, the commentaries for many of the ''Half-Life'' games mention this style of game design. Show the player something, let them do that something, and then let them do that something while in a dangerous situation. Generally there isn't as much lag between the intial teaching and the usage of that skill, but it sorta counts.
** The Companion Cube itself is the result of a failed attempt at one of these. Players were supposed to figure out for themselves that the cube would be necessary throughout the chamber, but too many testers abandoned it and got stuck. So they just had GLADOS outright tell you the cube was meant to accompany you through the entire chamber and spun it into a gag.
** The [[VideoGame/Portal2 sequel]] has another example: near the beginning, you trick the system responsible for throwing out defective turrets into throwing out working ones and keeping the defective ones. Soon afterwards, [=GLaDOS=] throws turrets at you -- which are defective. [[spoiler:Near the end of the game, Wheatley sets up an [[StupidityIsTheOnlyOption obvious death trap]]... full of defective turrets.]]
** ''Portal 2'' is a game where nostalgia fights to create an unrelenting march of Chekhov's Boomerangs, all while introducing new ones.

* In ''Literature/TheHungerGames'' The nightlock berries that Peeta accidentally kills Foxface with come up again after [[spoiler: it's announced that the new rule that there can be two winners of the Hunger Games if they are in the same district has been revoked, Katniss and Peeta use them to threaten to kill themselves and ensure there is no winner. They come up again in ''Mockingjay'' where the rebels inspired by these events create a suicide pill they name Nightlock (whether it's made from Nightlock berries is unknown) also saying Nightlock 3 times will turn the Holo into a bomb.]]

* The Cane of Pacci in ''VideoGame/TheLegendOfZeldaTheMinishCap''. You receive it early in the game, it helps for a while, it gets used less and less as you get further into the game and no truly new uses for it appear for quite some time...then all of a sudden, you need it again [[spoiler:in order to beat the FinalBoss]].
** Not all that uncommon in the other ''Zelda'' games, as the player's inventory can become rather stuffed.
** One of the more prominent examples is in ''[[VideoGame/TheLegendOfZeldaTwilightPrincess Twilight Princess]]''. Early in the game, Link, when talking to the mayor before leaving town, has to catch a runaway goat, stopping it in its tracks and throwing it to the side. This [[ChekhovsSkill later comes into play]] when Link is climbing DeathMountain (this time, against charging Gorons), and is even required to beat the mid-boss that he battles in the dungeon that follows immediately after climbing said mountain. This skill is pretty much forgotten about for the rest of the game, [[spoiler: until the battle against Ganon, where Link, in his Wolf form, must do this in order to expose his weak spot]].
* While most spells in ''VideoGame/{{LOOM}}'' are used only once, a few get used more than once -- especially the opening spell.
** Sometimes, you use a spell, and later you'll have to cast the same spell ''backwards'' to obtain the opposite effect (e.g. open/close)
*** Loom is a particularly interesting example because there are no items in the game. Most adventure games that require a character to use a 'recipe' for something give that character an item that lists the recipe, so you can turn back to it if you get stuck. In Loom, you have to write the spells down as you find them out, or you are screwed (unless you use a strategy guide, which generally wasn't possible in those days). And even a strategy guide might not help, since some of the spells are randomized for each playthrough.

* In ''VideoGame/MegaMan2'', the Bubble Lead is pretty much useless against every other enemy in the game... until you get to Wily's [[spoiler: Hologram]], in which it's the only weapon that causes actual damage to it instead of ''healing it to full'' like every other weapon.

* The ''WesternAnimation/TheOwlHouse'' episode "Labyrinth Runners" starts with a flashback to how Gus and Willow met -- Willow finds Gus having a breakdown in an empty classroom, and teaches him a breathing exercise to calm him down. This breathing exercise gets brought up multiple times throughout the episode; Gus teaches it to [[spoiler:Hunter]] when the latter starts having a panic attack, and [[spoiler:Hunter]]'s knowledge of the exercise helps convince Willow that he's on their side. In the climax of the episode, [[spoiler:Hunter]] tries to guide Gus through it when Gus goes into HeroicBSOD, but because he doesn't quite know how the exercise goes, it ends up looking more like he's trying to whistle through an asthma attack -- the sight of which makes Gus laugh, which snaps him out of it.

* OlderThanFeudalism: An example from Greek Mythology, starting with the Archaic ''Catalog of Women''. A boomerang on several levels: when Heracles (better known by his Roman name, Hercules) slayed the Hydra, he dipped his arrows in its poisonous blood thinking that SomedayThisWillComeInHandy. He winds up using it to kill a centaur named Nessos who meant to rape his (current) wife, Deianeira. Before he dies, though, the Nessos tells Deianeira to take his blood and use it as a love potion on Heracles, if the need should ever arise. She does so, and when she hears about Heracles' interest in the woman Iole, she anoints his clothes with it. The next morning, as Heracles burned sacrifice to the gods, the heat from the flames caused the Hydra's blood to eat away at his flesh, leading to his death. And then those arrows are used ''again'' by Philoctetes to mortally wound Paris during the Trojan War.

* In pre-ComicBook/{{Crisis|on Infinite Earths}} ''ComicBook/{{Superman}}'' comics, a minor [[UsefulNotes/TheSilverAgeOfComicBooks Silver Age]] story involved Superman gathering kryptonite from around the world, forming it into a small ''island'' in the ocean (there were a ''lot'' of kryptonite meteorites in those days!), and then propelling the whole thing into outer space to get rid of it. Still, it was UsefulNotes/{{the Silver Age|of Comic Books}}, so kryptonite kept turning up on Earth despite this. Years later, Creator/DCComics decided to stop using kryptonite as an easy plot device, so they had a freak accident destroy all the kryptonite on Earth, and the Superman comics went for a while with no (or at least fewer) stories involving the stuff. Writers missed it though, so years after ''that,'' they had the long-forgotten "Superman Island" of kryptonite return from space and scatter the stuff all over the world again.
* Creator/AlanMoore once wrote a story prophesying the end of the ComicBook/GreenLantern Corps. Fast-forward a decade or two, and it's become the basis for the ''ComicBook/BlackestNight'' event.
** Actually used twice. The "Blackest Night" Prophecy was also used in the early 1990's when the Green Lantern Corps was destroyed for the first time, after when Hal Jordan went mad with grief and became Parallax. "Blackest Night" was also the title of one of the comics leading to the end of that same arc, implying that Parallax/Jordan caused the Blackest Night. The Universe has since been rebooted and the prophecy retconned, however, so it's likely that in canon the first occurrence was just a warm-up.
*** The first one didn't include Sodam Yat or Ranxx the Sentient City, both mentioned in the original Creator/AlanMoore story.
* In one ''ComicStrip/{{Peanuts}}'' arc, Charlie Brown in lost in the woods, so Peppermint Patty and Marcie go out to look for him. Marcie brings supplies, including cold weather gear, food, water, [[ArsonMurderAndJaywalking and comic books.]] Eventually, it starts to snow, and because Patty is only wearing her sandals, her feet get cold. So Marcie tries to wrap her feet in the comic books. It works for a while, but eventually, the storm gets worse, and the hastily made comic bandage starts to fall apart. Fortunately, when the blizzard is at its worst, they find Charlie Brown and Snoopy, or rather they find them; they followed the trail of comic book pages.

* ComicBook/PostCrisis has the ''ComicBook/{{Superman}}'' storyline ''Ending Battle'', where dozens of super-villains gang up on Supes. During the fight, he disposes of Neutron by tossing him into orbit in outer-space. Two issues later, the villains are down to four but have cornered a worn-out Superman on a deserted island. Superman suddenly tells them that Neutron should fall out of orbit any moment now, which he does, provoking a nuclear blast that disrupts the fight and gives Superman a chance to leave after the BigBad.
* ''ComicBook/{{Transmetropolitan}}'': I-Pollen Damage, Source Gas and Spider's ''second'' back-up gun.

-->Twilight twisted around—and around and around and around—looking at her cutie mark, scared that it might have changed; it had not. Adorning Twilight’s flank was a pink six-pointed star surrounded by smaller white stars. “What—? No! The stars represent the spark of magic!”\\
“They do,” Celestia confirmed. "Is it so hard to believe they might also represent stars?”

* ''Fanfic/ThousandShinji'': Shinji keeps several magic jars storing four [[SpaceMarine Rubric Marines]], and he makes repeated use of them, but at the end it is [[spoiler:the ''TabletopGame/{{Warhammer 40000}}'' gods who emerge from them]].

* ''LightNovel/ACertainMagicalIndex'' has pulled this off a few times: the Capacity Down system, with the extremely useful effect of crippling any espers within its range, used in ''Railgun'' is later used against GROUP in volume 15. Body Crystal, a drug that amplifies an esper's powers, is a refinement of the red crystal developed in that same story arc. ''The Queen of the Adriatic Sea'' appears dealt with partway through the series, only to [[spoiler:resurface as a weapon against Fiamma of the Right during World War III.]] The author has also taken to introducing concepts and characters in one-off side stories only to have them appear in later primary story arcs (Leivina Birdway and her "Dawn-Colored Sunlight" magic cabal being a prime example).

* In ''LightNovel/TheFamiliarOfZero'', Princess Henrietta passed to Louise her mother's ring the "Water Ruby" as a good luck charm after assigning her to a mission in Albion. The ring became vital when it was used to convince Prince Wales of Albion that Louise is really Tristain's ambassador. [[spoiler: It is however more than just a Tristainian royal keepsake as it was later revealed to be essential in unlocking the secrets of Void magic.]]

* In ''LightNovel/NyarukoCrawlingWithLove'', Nyarko gives Mahiro a good luck charm[[note]]Which Creator/HPLovecraft fans will recognize as the Shining Trapezohedron[[/note]] in the first light novel (or the second episode of the TV series). It proves its use later that same story, letting him [[CallOnMe summon Nyarko in a time of great need]]. The Trapezohedron boomerangs back a few times, such as summoning Nyarko (who was left home with a cold) in ''Nyarko-San W'' Episode 10, but the most prominent example is in the third novel/episode 10, where [[spoiler:it acts as a PocketProtector and keeps [[FreakyFridayFlip Nyarko-in-Mahiro]] from being killed by the BigBad.]]

* In ''VideoGame/MegaManStarForce'', you get 5 cards to summon 5 Navis, each of which are used 3 times: after you get them, in the final area, and in an optional puzzle. Thing is, you may not realize the last one.

* In ''VideoGame/MetalGearSolid3'', Snake begins the second and main storyline with two pieces of nifty but largely useless equipment, a suicide pill and an antidote which can be strategically used to play dead. As the player gets better camouflage packs and weapons it becomes less and less useful to the point where the player has no real need to use either until a certain boss fight later [[spoiler:where Snake is killed while in the world of the dead and the player has to use the antidote to 'wake up' to progress in the game.]]

%%* ''WesternAnimation/DespicableMe''. Anti-gravity serum + minion. HilarityEnsues.

* Creator/AlanMoore once wrote a story prophesying the end of the Comicbook/GreenLantern Corps. Fast-forward a decade or two, and it's become the basis for the ''ComicBook/BlackestNight'' event.

* In ''Film/GuardiansOfTheGalaxy'' it's mentioned about halfway through the movie that a group of people successfully controlled an Infinity Stone by sharing the burden. Near the end of the movie, the Guardians use the same method to stop Ronan using the Power Stone. In prompt 50 of ''[[https://archiveofourown.org/works/18270659/chapters/45904030 Calling You Out]]'', Quill makes everyone grab onto Tony when he uses the Infinity Stones to erase Thanos' forces, which allows him to survive, albeit with a crippled arm.

** In ''Literature/HarryPotterAndTheOrderOfThePhoenix'' Zachariah Smith's comment about Expelliarmus not being useful against Voldemort is amusing, it's also counts as a boomerang, because in [[Literature/HarryPotterAndTheDeathlyHallows Deathly Hallows]] [[spoiler: Harry's identity is revealed by the fact that Expelliarmus is his signature move]].

* In ''Literature/TheHungerGames'' The nightlock berries that Peeta accidentally kills Foxface with come up again after [[spoiler: it's announced that the new rule that there can be two winners of the Hunger Games if they are in the same district has been revoked, Katniss and Peeta use them to threaten to kill themselves and ensure there is no winner. They come up again in Mockingjay where the rebels inspired by these events create a suicide pill they name Nightlock (whether it's made from Nightlock berries is unknown) also saying Nightlock 3 times will turn the Holo into a bomb.]]

* VideoGame/DragonQuestVI has a few as well:

* Paula's Pray ability in ''Videogame/EarthBound1994'' starts as a useful, if unpredictable skill, that takes a back seat to her more reliable psychic powers. [[spoiler:Then you need to pray for a chance of beating the final boss.]]

** The [[VideoGame/{{Portal2}} sequel]] has another example: near the beginning, you trick the system responsible for throwing out defective turrets into throwing out working ones and keeping the defective ones. Soon afterwards, [=GLaDOS=] throws turrets at you -- which are defective. [[spoiler:Near the end of the game, Wheatley sets up an [[StupidityIsTheOnlyOption obvious death trap]]... full of defective turrets.]]

[[folder:Web Comics]]

* ''Webcomic/{{Sinfest}}'': Glitter points really come in handy a lot.

* Bleach: Ichigo's nature as a hybrid is used many times in the story ([[spoiler: Hollow Ichigo claims that he's the spirit of his Zanpakuto at the start of the series. In Thousand Year Bliod War arc, i was revealed that [[CassandraTruth he's manifestation of Ichigo's Shinigami powers as Zanpakuto]]]]).

** A good specific example is the Ancient communication stones: Introduced originally for a humorous clip show episode where a random schmuck finds out about the Stargate program through it, then used a season later to contact the Ori galaxy, and then used again in an Atlantis episode a few years after that.
*** And then it became a fundamental plot device in ''Series/StargateUniverse''.