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Chekhov's Boomerang

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An item gets used. You relax a bit, maybe admire the way it fits into the plot if it's done well. But then, when you were least expecting it, it gets used again. Thanks to The Law of Conservation of Detail, you had put the item out of your mind because it had served its purpose—but what you didn't realize was that it wasn't a single-shot Chekhov's Gun and is actually coming back.

Particularly common in Adventure Games, where a particular item, setting, or character might get used three or four times. While this is a good thing in principle, being more realistic, leading to fewer loose ends, and going some way to countering Stupidity Is the Only Option, it can throw newbies to the genre who might get stuck on a puzzle for hours because they didn't realize that they'd had an item all the time, they'd just forgotten about it. Of course, this cuts both ways: you might try out something that worked before, but this time it doesn't.

Compare Brick Joke (the gun is dismissed and forgotten before it's used even once, and then comes back). The player may have to apply Chekhov's Boomerang in video games for Final Exam Bosses.


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    Anime & Manga 
  • Angel Beats! has "My Song", a ballad played by Iwasawa at the beginning of Episode 3. She is told not to play it because it would not be useful as a distraction for the school's students. Later in the episode, she plays it before accepting her past and disappearing.
  • Three examples from Black Butler:
    • First there’s an early mention that Aleister Chamber is involved with black magic groups, which overlaps with Chekhov's Hobby. Later on he turns out to be part of the Phoenix Society and tries to use the Bizarre Dolls for his own purposes. In the next arc, his connections to the Phoenix Society allow his nephew, Edgar Redmond, to contact the Undertaker.
    • During the School Arc, the elephant that Soma rides into school on also becomes important twice- and yet it still manages to be hilarious every time it shows up. First it gets spooked and destroys Maurice Cole’s room, forcing him to share with Soma and giving Soma the chance to catch him sending notes to his underlings and get photos of his real face. Then Sebastian uses it to transport water during the fire.
    • In the both seasons of the anime, Ciel’s ring has actual plot importance, although this trope only applies in the second season because in the first season it serves an entirely different purpose. It houses his soul, prompting his memory loss and the entire second season. Then a different ring is later used to store Aloise’s soul the same way Ciel’s ring was used. The effect lasts much longer (in terms of screen time, at least) and plays an even more crucial role in the plot then the first example does.
  • Bleach: Ichigo's nature as a hybrid is used many times in the story (Hollow Ichigo claims that he's the spirit of his Zanpakuto at the start of the series. In Thousand Year Bliod War arc, it's revealed that he's manifestation of Ichigo's Shinigami powers as Zanpakuto).
  • A Certain Magical Index 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 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).
  • Code Geass makes Suzaku into a Chekhov's Gunman riding a boomerang when Zero Geasses him to "Live!" in order to prevent a Heroic Sacrifice (for the sake of the villains, stopping his own goals from being achieved) that could have killed Lelouch, Kallen, and potentially Euphemia, all of which are Suzaku's own friends, as well as collapse much of the Black Knight organisation. Later, his Knightmare Frame is armed with a FLEIYA, which he swears up and down he won't actually use. This lasts until Kallen shows up, full of rage and piloting a superior Knightmare. She tears him to shreds and when the Geass activates, the only way he can "live" is to fire the nuke and kill half of Tokyo. It activates several other times as well, this is just the most noteworthy one.
    • A number of characters prove to be recurring when we thought they'd only be of the one-shot variety. Most of the characters (the named ones, anyhow) in the series have a series of overlapping relationships, and so show up in multiple contexts. Lady Marianne receives several different interpretations, none of which we were expecting. As well, Nina Einstein starts as a quiet classmate of Lelouch, who then meets Princess Euphemia and develops a crush, who then attempts to build a bomb in the school basement when said crush goes crazy and dies, who then shows up a year later building the bomb properly, who then sees it used on Tokyo, and then she finally shows up working for Lelouch, building a device that stops the AU-nuke from being used again. Villetta, one of the first characters to be geassed by Lelouch, proves to be one of the most troublesome for him at various key moments.
  • Pulled off in a massive scale in the last arc of the Desert Punk anime, where half the apparently one-shot characters all show back up as part of La Résistance.
  • The Ultra Sacred water (presumably the water from the Garlic Junior arc of Z, and not similarly named waters from Dragon Ball) in Dragon Ball GT, which was useful to get the characters cured from Baby's control.
  • Dr. STONE: As a show that primarily revolves around a Science Hero, this comes up a lot. Every early invention ends up becoming part of a later one, or to make the tools to make another invention. As Senku says, science is all about building on what has come before, and nowhere is that more obvious than with tools. More specifically:
    • The powdered seashells start out being used as soap, but they end up as a key component for gunpowder and later the sulfa drug.
    • The pulley system Senku makes to lift the tree off Kohaku in their first meeting becomes the basis of the first wheeled cart.
    • The hand-powered electric generator gets slotted into the waterwheel for hydroelectric power.
  • Fairy Tail:
    • Shortly after the end of her arc we find out that Erza, who we saw in an earlier chapter losing an eye when she was young, got a fake magic eye as a replacement. Because of this she only receives half the blast from a petrification gaze and is easily broken out the spell. After about another arc people forget she ever lost an eye at all, until she uses the fake one to see through an illusion.
    • At the end of the Tower of Heaven Arc, Natsu first uses his Dragon Force by devouring the highly-concentrated magical energy of the Etherion crystals to defeat Jellal. At the climax of the Nirvana Arc, Jellal, now an amnesiac good guy who vaguely remembers the events of said arc, gives Natsu a power up in the form of his remaining magical energy in a powerful flame spell so Natsu can use Dragon Force again to defeat Zero. Then Sting and Rogue at the climax of their fight in the Grand Magic Games reveal they can use Dragon Force without an outside source. Then, in the Tartaros Arc Wendy remembers how Natsu activated Dragon Force and replicates it via absorbing the high ethernano concentration in the air around Face to activate her own version and fight Ezel, while Natsu manages to tap into Dragon Force against Mard Geer without an outside source of energy on his own. Finally, during the final arc Wendy reveals she can use Dragon Force naturally after training, Gajeel obtains it by absorbing the Demon Barrier Particles of Bloodman, and Natsu once again uses it without outside help to help defeat Zeref.
    • At the climax of the Tenrou Island Arc, Natsu unlocks Lightning-Flame Dragon Mode when fellow Dragon Slayer Laxus gives him his magic to fight Hades. During the Grand Magic Games, Gajeel remembers this and chooses to replicate it while fighting Rogue's Superpowered Evil Side to obtain Iron Shadow Dragon Mode. Then the Rogue from the Bad Future reveals he unlocked his own dual mode via killing and devouring his best friend Sting's magic to obtain White-Shadow Dragon Mode. Finally, in the Alvarez Empire Arc, Rogue replicates what Gajeel did to him to let Sting obtain White-Shadow Dragon Mode to fight Larcade of the Spriggan 12, which serves as a fitting ironic twist to what happened to their future counterparts.
    • In the Tartaros arc, it's revealed Igneel and the other dragons used the Dragon Soul technique to enter the Dragon Slayers' bodies to both protect them and to extend their own lifespans after being fatally injured long ago by Acnologia, thus explaining their long disappearance. In Fairy Tail: Dragon Cry, the Big Bad Animus is revealed to be a dragon that used that same technique to save himself and a dying Sonya after he was fatally injured by Acnologia, but because Sonya wasn't a Dragon Slayer he couldn't free himself like they could, which is why he sought out the Dragon Cry to give himself the power to free himself from her body.
    • The Final Battle is ultimately won through the reuse of one-off techniques:
      • The Sirius Island arc introduces two spells: Fairy Sphere, a defensive spell that Mavis seals Fairy Tail inside to protect them from Acnologia on Sirius Island; and Magilty Sense, Merudy's signature magic, which she reveals earlier in the final arc can multiply other people's power. Incidentally, both spells require a deep, emotional bond between others to be properly cast. Lucy — one of the most empathetic characters in the series, as noted in Fairy Tail the Movie: Phoenix Priestess — figures out that they can use Fairy Sphere to seal Acnologia away, and Merudy uses her Magilty Sense to link Lucy with every wizard on the continent to power the spell.
      • Wendy picks up on Irene's ability to enchant other objects and people with her own magic to get out of a "Freaky Friday" Flip and power up Erza's sword. When faced with Acnologia's disembodied soul, Wendy uses this technique to transfer her and the other Dragon Slayers' magic into Natsu, which proves to be more magic than Acnologia can handle when Natsu slams all of it into him at once while he's paralyzed by Fairy Sphere's activation.
  • In The Familiar of Zero, 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. 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.
  • Fullmetal Alchemist, simply put, does not have throwaway characters. Characters thought to be one time bits will show up in given time. Corpses long forgotten will re-emerge.
    • Remember Kimblee? Guy who blows stuff up, saves Ed once, yada-yada? Well, he's dead and absorbed, so now we don't have to see him ever agai-oh wait, there he is inside Pride, stopping the little bastard from taking over Ed's body. And that is without mentioning his Philosopher's Stone.
    • Remember Havoc's girlfriend? He was finally going to have a great relationship, but then Mustang makes him dump her. Well, that was pretty funny. She won't be coming back aga-Oh hello, Lust...
    • The idea of the exchange with Truth comes back again and again!
    • Even in Brotherhood, based more closely off the manga. You can safely ignore Isaac Mcdougall, the filler character made just for this anime and the subject of the one filler episode, at the end of which he dies, right? There's no way his crazy OC plot will come back in later episodes, right? Wrong.
    • In a flashback to Xerxes, we see Father lied to the king about where the nation-spanning transmutation circle was centered, leaving the king to get turned into a Philosopher stone with the rest of the country. Near the end of the manga, he pulls this same trick again, as the apparent center the heroes were trying to keep Father away from was a decoy; the real one was under his chessboard.
  • In Heroman Joey activates Heroman's Augment ability in Episode 4. Fast-forward 19 episodes later, and it is used to spectacular effect.
  • JoJo's Bizarre Adventure: Diamond is Unbreakable: In Morioh, there's a cursed alley that a person must never turn around when exiting so they won't be Dragged Off to Hell. 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 to finish off the spirit of her murderer Yoshikage Kira.
  • Remember that time way back near the beginning of Magical Girl Lyrical Nanoha where the heroine used a little spell called "Area Search?" Well, in Magical Girl Lyrical Nanoha StrikerS, it comes back big time. Nanoha uses it to sniff out Quattro, before blasting through the ship's bulkheads and taking her out with a multi-cartridge-enhanced Divine Buster.
  • Mobile Suit Gundam 00: in Episode 19, Tieria utilized the almost secret of his Gundam Virtue — Nadleeh and its Trial System — which control any mobile suit connected to the Veda computer. The Trial System demonstrates its ability to stop the Gundam Thrones dead in their tracks but is disabled by someone hacked into Veda. Never to be seen again, especially not after being disabled and the original Gundams being decimated at the end of the first season? Dead wrong. The Trial System makes a surprising victory appearance through the Seravee/Seraphim just after control of Veda is wrestled back from Ribbons during the second to final episode and stops a neverending swarm of kamikaze Trans-Am Gundam.
    • After realizing Veda might no longer be safe, Celestial Being programs new operating systems for the Gundams so that they can operate independently of Veda (in Season 1). They also have to fall back on this strategy quickly after speculating on the risk. During the final episode (of Season 2), Ribbons resorts to the Veda-independent Reborns Gundam and uses it to destroy Seraphim, which was using it's Trial System to disable all of the Veda-connected villains.
  • Monster: Johann's candy, the story books, Three Frogs, and many others.
  • In Naruto:
    • Uchiha Shisui's only role seems to be to explain whom Itachi killed to get his Mangekyou Sharingan. 237 chapters later, it is revealed that the Sharingan that Danzo hid under his eye bandage belonged to him. He returns again during the Fourth Ninja World War, when his other Sharingan helps a resurrected Itachi break from Kabuto's Edo Tensei Mind Control.
    • Orochimaru uses the Reanimation Jutsu during the Konoha Crush to fight Hiruzen Sarutobi, the Third Hokage. And the end of Part II:
      • Kabuto uses the same jutsu to summon many shinobi from the dead and form his own army with it.
      • Orochimaru summons previous Hokage from the dead to fight Obito and Madara
    • Sasuke's Shadow Shuriken technique, used once in the first arc, is used again over 350 chapters later when he is fighting Itachi. It returns again another 50 chapters later when Naruto uses it with a Rasenshuriken against Pain.
    • Naruto's Rasenshuriken technique, initially a melee attack, was used a few times during the Immortals Arc. Due to the damage it causes to his own body, the Hokage bans him from using it any further. About 100 chapters later, Naruto gets around the problem by using Sage Mode to convert it to a projectile attack. It still has another limitation in that he can only use it a few times, rendering it useless if it misses the target or the opponent dodges it. He gets around that problem too, about another 100 chapters later, and now it is remote-controllable using his other Super Mode.
    • Upon returning from his training with Jiraiya, Naruto gifts Kakashi one of Jiraiya's novels. He uses it to good effect during Kakashi's bell test. It is never mentioned again until the Pain arc, during which it becomes important to decode a message.
    • Another one of Jiraiya's novels about a battle against a rogue ninja, serves as an inspiration to Namikaze Minato to choose his son's name. It is brought up again during the Pain arc for a different reason.
    • Way back in chapter 8, Kakashi warns Team 7, after a very poor demonstration of teamwork, that if they do not improve, a time may come when they are forced to sacrifice a team member for their mission. To emphasise the point, he tells Sakura to kill Naruto or else he would kill Sasuke. This situation is played out in Kakashi's backstory, where he had to choose between rescuing his teammate Rin and completing his mission, and eventually leads to what everyone considered Obito's death. The situation appears again in Nagato's backstory later, where he had to choose between killing either of his two teammates, and that leads to Yahiko's death. Still later, it is revealed that Kakashi was a witness to another such situation, wherein to save Konoha, Kakashi was forced to kill Rin, who was forcibly made a Jinchuriki for the purpose of attacking Konoha.
  • Negima! Magister Negi Magi has one that crosses continuities; an antagonist attacks Negi using an attack that originated in Ken Akamatsu's previous manga Love Hina. There's even Word of God to support the idea that they take place in the same universe.
    • Chao Lingshen's involvement in the plot counts as this; after her first appearance, she functions as the Big Bad about a dozen volumes later. Then another dozen or so volumes after that, she becomes plot-important again.
    • Also Fate Averruncus. He shows up in the Kyoto arc (Volumes 4-6), working as a henchman. Fifteen or so volumes later, he makes a reappearance. Turns out he's the Big Bad.
  • In Nyaruko: Crawling with Love!, Nyarko gives Mahiro a good luck charmnote  in the first light novel (or the second episode of the TV series). It proves its use later that same story, letting him 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 it acts as a Pocket Protector and keeps Nyarko-in-Mahiro from being killed by the Big Bad.
  • One Piece does this frequently with some of the cast (like Hatchi and Laboon) ending up important hundreds of chapters after they were introduced. In fact "Oda never forgets" has become something of a meme among One Piece fandom.
    • A good example: Ace's tattoo. Looks misspelled, right? Well, after his introduction, during the Marineford arc, we find out the crossed out S was the jolly Roger of his and Luffy's third brother, Sabo, who died. Then hundreds of chapters after that we find out Sabo actually lived but with amnesia, and only reading about Ace's death at Marineford brought back his memories before putting him in a coma, and he later shows up to help Luffy. So, what looked like a little quirk in a character's design in the Alabasta Saga was really foreshadowing for something in the Dressrosa saga, well over four hundred chapters later.
    • Even the villains of previous arcs get this treatment by Oda. Notable examples include Buggy, Mr 2, Mr 1, Blackbeard, and even Crocodile. Caesar as well, even though he was defeated in the Punk Hazard Arc, he proves to have a pivotal role up to the Whole Cake Island Arc.
  • Pokémon Adventures manga.
    • Yellow turns up in the second chapter as the protagonist and as a girl, Lance turns out to be the guy instructing Silver, Ruby summons Celebi in the RS saga, "Guile Hideout" turns out to be Archie, and the whole Emerald saga was a ploy to change the previous chapter's protagonists back to normal from being petrified.
    • On the object end of things, there's the Grand Meteor, the Rainbow and Silver Wings, the memory firelighter, and Blue's Silph Scope with two or more convenient uses after their initial appearance. There are probably more.
  • Rave Master:
    • In Volume 6, when Haru is facing down Sieg, he's briefly able to get past his magical defenses by using the Eisenmeteor form of his sword, having realized that magical defenses only work on magic-infused items. Much later, Sieg is facing down Haja the Infinite, who has unlimited magic power. Unable to beat Haja with sheer magic strength, he instead rams him through the heart with a staff devoid of magic, having remembered what Haru said and realizing that Haja would be unable to block it.
    • During the fight with Orge, Musica is able to neutralize one of his goldclaimer techniques, pointing out the basic alchemy process between metals is all the same with the only difference being power. In Volume 32, when Musica attempts to forge a new blade for Haru's Ten Powers sword, he remembers that instance and instead uses his alchemy powers to make the blade instead of trying to master swordsmithing in a short time.
  • Lancia's Ring in Reborn! (2004). A small gift from Lancia to Tsuna in the end of the Varia Arc, forgetting about it causes Tsuna, Gokudera, and Lal Mirch to be attacked by a Strau Mosca, then be found by TYL!Yamamoto. Then, at the very end of the Future Arc, during the first part of Tsuna and Byakuran's final battle, it's having the ring in his breast pocket that prevents Tsuna from being killed by Byakuran's Mini White Dragon.
  • Sanosuke's Zanbattou in Rurouni Kenshin. Just when you thought it was gone for good after his fight with Kenshin, it reappears in his fight with Inui: This time, held together with GIGANTIC STAPLES.
    • Sanosuke also makes use of this trope a second time in the anime only Shogo Amakusa arc when he unexpectedly gives Shozo the same bombs which he used against Shishio's battleship: Purgatory. Only 31 episodes later.
  • The first season of Star Blazers/Space Battleship Yamato was fairly episodic in nature, and usually involved the Gamilons trying a particular plan or gizmo against the heroes which would not turn up again. One episode involved a tract of space laced with floating space mines. Another episode had a teleportation device that could make a Gamilon battleship appear out of nowhere. In the second season, long after we'd forgotten about both, Desslok brilliantly combined the two by teleporting a mess of space mines directly in front of the ship's Wave-Motion Gun, so they can't fire it without blowing up their own ship. Clever guy, Desslok.
  • In the first episode of animated series of ''Super Robot Wars Original Generation: The Inspector'', Axel apparently kills Beowulf (the Mirror Universe Kyosuke) with his mecha's Rocket Punch. However, Beowulf turns up alive and well and becomes the Big Bad of the series, handily trouncing the heroes. When all hope looks lost, Kyosuke sees the Rocket Punch buried in the Gespenst Mk-III's torso and strikes it, pushing it into the Mk-III's cockpit and crushing Beowulf.
  • The Lagann Impact in Tengen Toppa Gurren Lagann might count: its primary use is to hijack enemy Ganmen which it does successfully nearly all of the time, the only exception being the Lazengann which blew up its own arm before it could've been taken over. Afterwards, it's completely forgotten... until the final battle where it One Hit Kills the Anti-Spiral.
  • In Xxx Holic and Tsubasa -RESERVoir CHRoNiCLE- (a linked story so confusing they use each others guns) notes that a person's true name gives you power over them. Watanuki in the first series gives his name to Yuuko. Later, it's revealed that this name is a fake, a decoy. He doesn't actually know his real name. But then, Fay turns out to be the main character Fay's twin brother, who made a wish for him to get free, and 'Fay' has been using his name since. Think it's done? Wrong! Kurogane reveals that only Tomoyo knows his true name. Also Syaoran lied at the beginning of the story about what his name was, and is using the name of his father. However, it is likely that uh... Mugetsu's name is real, at least. Apart from that, who knows?
  • In Yu-Gi-Oh! GX The Phantom Demons/Sacred Beasts cards are the main plot point of Season 1. They're defeated and sealed away. They suddenly become relevant again mid-way through Season 3 when the new villain obtains them and uses them in a single duel. They then disappear again. Towards the end of Season 3, they make another appearance. And then they're never mentioned again, despite having the power to destroy the world.
    • This trope can be applied to numerous cards in the series. Due to the formula, many cards make a single appearance and never show up again. Others are used extremely often. However, if a card is used twice and makes a major comeback in later, more important duels, if they're cards that tip the balance to the hero's favor, and if they're cards the viewer has forgotten about, then the trope applies.
  • Yui Kamio Lets Loose: The Yui in White's wig Kiito wore in Chapter 6 is used by Yui in Black to disguise as the other one in Chapter 9.
  • The Spirit Egg in the anime version of YuYu Hakusho. Initially, Yusuke is told that when it hatches, the spirit animal within will resurrect him, then he later uses it up to save Keiko from a fire. Several arcs later, it turns out the egg wasn't destroyed but simply used up all it's energy and it's now about to hatch into his spirit guide.

    Comic Books 
  • Superman:
    • A minor Silver Age story involved Superman gathering kryptonite from around the world, forming it into a small island in the ocean, and then propelling the whole thing into outer space to get rid of it. Still, kryptonite kept turning up on Earth despite this. Years later, DC Comics decided to stop using kryptonite as an easy plot device, so in Kryptonite Nevermore a freak accident destroys 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.
    • In Ending Battle, 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 Big Bad.
  • Green Lantern: 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 Blackest Night 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 Sonic the Hedgehog (Archie Comics), Dr. Eggman uses the blue Chaos Emerald to initiate a Cosmic Retcon, 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 Mega Man (Archie Comics) universe, setting the stage for the two franchises' crossover.
  • X-Men: Gambit falls somewhere between this and Forgotten Phlebotinum. 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.

    Comic Strips 
  • In one 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, 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.

    Fairy Tales 
  • Alexander Afanasyev's "The Soldier And Death": A beggar gives the titular soldier a magic sack, which has the power to entrap any creature inside if the owner says something along the lines of "Get in the sack!" The soldier uses this to catch a bunch of devils in the mansion, and it is then forgotten until the soldier uses it trap Death.

    Fan Works 
  • A Growing Affection:
    • Naruto's Five Points Rasengan might qualify; In book 1 its development is discussed, then he uses it in a fight in the first half of the book. Then in the middle of book 2 he shows it in the Jonin Trials, but does not use it in combat. It gets used again near the end of book 3, and again near the end of book 4.
    • A better example might be the Reaper Death Seal dividing the Fox's chakra in Naruto. When the Fox merges with Naruto, the Akatsuki scientists recognize that the seals are gone; they have been talking about the Eight Trigrams Divination Seal and Divine Arts: Zodiac Seal by name, but one could assume the third seal is gone, too. But at the end of book 3, the Reaper Seal suddenly reappears on Naruto as the Reaper uses it as a medium to send the Hokages back to stall Orochimaru. So again, one might think the seal is gone. Instead it shows up again at the end of book 4, when Naruto removes it to get the rest of the Fox's chakra, refilling his own reserves and unlocking his Shin Tensei Kitsune jutsu.
  • In Guardians of the Galaxy (2014) 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 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.
  • Dirty Sympathy: Apollo's first-aid kit. It is mentioned in the beginning of the story when Apollo has to go the pharmacy to pick up burn cream and bandages because he didn't have them in his kit and uses it to treat Klavier's injuries and is seen again when he uses it to treat Trucy's firework burns. When Phoenix and Edgeworth try to piece together why Klavier and Apollo suddenly left, they find the first aid kit in Apollo's room which Edgeworth uses to confirm Apollo's story that he was physically abused by his former boss.
    • Klavier's ring. Klavier accidentally left it behind after sleeping with Apollo, telling Daryan that he lost it after sleeping with a groupie. Apollo tries to return it after he reunites with Klavier, but Klavier lets him keep it because it would be suspicious for him to get it back. When Phoenix finds it in Apollo's room after Apollo suddenly leaves, he realizes that Apollo and Klavier, whom he thought were simply colleagues, were actually lovers.
  • Eleutherophobia: Tom acquires Jake's DNA near the end of The Day the Earth Stood Still to calm him down. He later morphs into Jake for subterfuge in The Thing from Another World, and again in Escape from L.A.
  • MLP fanfic Sharing the Night makes one of Twilight's cutie mark when she accidentally assumes control of the stars
    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?"
  • Son of the Desert: Edward snarks about Roy not knowing anything about Ishvalans after Ed manages to talk Scar down in Ishvalan without Roy knowing what they're saying. Roy later learns enough language and culture to apologize to Edward in Ishvalan. In the story's climax, Roy gives Ed a traditional marriage proposal.
  • Thousand Shinji: Shinji keeps several magic jars storing four Rubric Marines, and he makes repeated use of them, but at the end it is the Chaos gods who emerge from them.
  • What You Knead: When Sasuke first unlocks the Sharingan, his inability to control it means that he memorizes a lot of random, 'pointless' moments. This helps him catch that Kakashi's condition is steadily deteriorating. Later on, the memories he accidentally memorized come back into play when he's fighting the cursed seal's influence by remembering those happier times.

    Films — Animation 
  • Famed Mexican artist Frida Kahlo in Coco. She's first used as a disguise by Hector, which segues into him knowing where to take Miguel to find Ernesto de la Cruz because he borrowed the costume from a show Frida was planning with him. Miguel ends up meeting the real Frida as she prepares for the show, and she's the one to tell him where to find de la Cruz — at a very exclusive party at his private tower. She also compliments his artistic instincts for good measure. Later on, Hector ends up getting into the party by disguising himself as Frida again, and Miguel and his family all disguise themselves as Frida with her blessing to get to de la Cruz in the climax.
    Frida Kahlo: Good luck, muchacho.
    Miguel: Gracias, Frida!
  • Scooby-Doo! WrestleMania Mystery has Scooby-Doo's imitation of Sin Cara's dance. Scooby initially uses it to win a video game and be invited to WWE City. Later on, he's hypnotized and unknowingly uses the dance to steal the championship belt. Finally, when being forced to fight for his and Shaggy's freedom against Kane, he uses the dance at Shaggy's suggestion and near-effortlessly fends off the fearsome wrestler.
  • The character of Bonnie from Toy Story 3 who first plays a part in rescuing Woody from the daycare centre and helping him find Andy's house. She then comes back into play at the end of the movie where Woody writes down her street address on the box of toys so Andy can leave them with her rather than locking them up in the attic.
  • Derek's bow in The Swan Princess. When he first sees Odette transforming from swan back to human at the lake, Derek tosses it aside and forgets to grab it in his haste to leave. Rothbart finds it, tipping him off that Derek has found Odette, and later throws it into the lake. During the climatic fight between Derek and Rothbart, Puffin remembers the bow is in the lake and sends Jean-Bob and Speed to retrieve so Derek has a weapon to fight with.
  • Buzz's wings in Toy Story. Used first by Buzz to try and prove he can fly, then when he tries and fails to fly in Sid's house (resulting in a broken arm), and finally used in the climax to separate himself and Woody from the rocket before it blows up, and seconds later when "falling with style".
  • Turning Red: Mei's friends singing "Nobody Like U" happens three times throughout the movie. First to establish their friendship with Mei, then again to cheer up a distraught post-transformation Mei, then finally to help perform the red moon ritual.
  • Zootopia has Judy's carrot-shaped pen/recorder. It's how she blackmails Nick into helping her, which is then used by Nick to tape Judy's teary-eyed confession that she needs him. It is finally used to tape Bellwether's confession.

    Films — Live-Action 
  • Back to the Future:
    • The hoverboard in the Back to the Future sequels. At the end of Part II, Marty uses a hoverboard he brought back from 2015 to get back Gray's Sports Almanac. He uses the hoverboard again at the end of Part III.
    • Lightning being enough to qualify for the 1.21 gigawatts. Obviously important in the first film, then it works again accidentally in the second.
    • Bullet-proof vest, too. All three films. Sort of.
  • Vijay's "786" badge in Deewaar.
    • First, it saves him by stopping the bullet when he's shot by one of Samant's men while stealing the gold back.
    • Later, it saves him when Samant's men try to assassinate him. Anita notices that he left it on the bar counter, and rushes after him to return it. She drops it and they both go to pick it up right when Samant's men fire, causing the shots to miss them both.
  • William Cage, the protagonist of Edge of Tomorrow observes a soldier strapping a claymore explosive to himself prior to going into battle as if preparing for a Taking You with Me scenario. A few scenes later, the mine ends up used (albeit not by the same soldier) for exactly that purpose against a charging alien. The Chekhov's Gun fired, most in the audience will forget about it after that. Only, because of the "Groundhog Day" Loop nature of the film, the mine reappears later, strapped to the same soldier as before, and is used for another Taking You with Me moment against a wave of charging hostiles.
  • In Everything Everywhere All at Once, the hot dog fingers universe seems at first like a joke timeline, as it doesn't give Evelyn any abilities like verse-jumping is meant for.note  It later becomes clear that experiencing it actually allowed Evelyn to understand, respect, and sympathize with Deirdre, as well as learn more about herself. In the climax, it turns out the hot dog fingers universe actually did have a power more in line with other verse-jumps it could bestow upon Evelyn: extreme foot dexterity, since they can't use their fingers, which she uses to get out of a situation where her arms are held down.
  • GI Joe The Rise Of Cobra: The tracking device.
  • Glass Onion: Miles Bron uses a butane torch early in the film to demonstrate how sensitive the security system on The Mona Lisa is. Late in the film he uses it again to destroy the evidence he killed Andi. It's then forgotten for a few minutes until Helen uses it to ignite spilled liquor and detonate the Klear power system.
  • Doug's statue-impaled mattress in The Hangover.
  • History of the World Part I: "Only a miracle can save us now!" note 
  • The rat poison in The Housemaid. Dong-sik's son Chang-soon thinks Myung-sook poisoned his water with it, so she drinks the water instead. Then she later tricks Chang-soon into thinking she poisoned him, causing him to run off in a panic, fall down the stairs, and die. Then Mrs. Kim tries to kill her with it, but it turns out that Myung-sook had switched out the rat poison for sugar water. Then Myung-sook and Dong-sik kill themselves by drinking the rat poison.
  • Big Jim Slade in The Kentucky Fried Movie.
  • All of the Matt Helm films starring Dean Martin have at least one of these.
  • The ivory pipe in National Treasure. It's almost a Swiss Army MacGuffin.
  • Oblivion (2013): The fact that drone power cores are pretty devastating when they go off comes to bite both sides of the conflict in the ass a few times.
  • Odd Obsession: The insecticide and cleanser cans. One's in a red can and the other's in a green can, and it is established that Hara is color-blind and can't tell the difference between cans. Hara decides to switch the contents of the cans so that she doesn't mix them up. What happens? Well, Tomiko decides to kill her mother and her faithless fiancé, so she does their tea with poison — except that the poison is actually the cleanser, so all she does is give their tea a funny taste. However, it turns out that in addition to illogically switching out what's in the cans, Hara also quite logically marked the poison can with "poison" on the bottom. After looking at the bottom of the can and confirming that it is in fact poison, Hara dumps it on top of the salad, and thus murders all of the other three.
  • Pirates of the Caribbean:
    • Jack's compass. It is introduced in the first film as a (presumably broken) compass that doesn't point north, however later in the movie Jack uses it to lead the Interceptor to the Isla de Muerta. It then becomes a sort of MacGuffin in Dead Man's Chest when it is revealed to lead the user to whatever they want most. Indeed, it has been used in every Pirates movie ever since, including the third and fourth ones.
  • Subverted in A Quiet Place with the nail sticking out of the basement stairs, which Evelyn steps on. Later in the movie when the characters go back down the stairs, there's a closeup showing that the nail is still there and uncovered. However, it never comes up again.
  • In Storm Over Asia, the Mongol herder protagonist has to flee for his life when the Evil Colonialist cheats him over the price of a fox pelt, leading to a violent confrontation. Much later in the film, the herder is outraged to see the fox pelt he was cheated over draped around the shoulders of a colonialist officer's wife.
  • In Treasure Island (1950) Long John Silver gives Jim Hawkins a small pistol, which Jim later uses to save himself from a pirate. At the end of the movie when Silver has been captured, he grabs the pistol back and uses it to turn the tables on Squire Trelawney and make his escape.
  • Uncut Gems has a particularly fast one. After the joke about Howard's door sticking, the gun goes off during the climax when Howard traps Arno and his goons in there. After being let out, one of the gangsters is enraged and shoots Howard. Arno tries to escape, but the door sticks again, leading to his death.

  • Castle Hangnail:
    • Early in the book, Molly tries to solve a problem involving a donkey by adapting a spell that was designed to be used on cows. As the story progresses, she solves several more problems by using the same spell again, each time on a different kind of animal and never on an actual cow.
    • The one bit of really impressive magic Molly knows to begin with is a spell that makes her shadow detach itself and do a dance. It turns out to be useful during a confrontation with a crooked property developer, and then again at the climax.
  • The Book from Baden Dark: In order to escape from Elstenwick, Marcel casts an invisibility spell on himself. Later, in Baden Dark, Marcel casts the spell in order to get away from Bea and Fergus, who have become distrustful of him.
  • In The Book of Three, the first of the The Chronicles of Prydain series, Taran encounters and nurses a baby gywthaint (a hostile bird species enslaved by the Big Bad) back to health. Most readers saw an Androcles' Lion moment coming, and were unsurprised when it repaid the favor at the end of the book. It was then probably forgotten about, making its return and Heroic Sacrifice in the final book all the more shocking.
  • In Daemon, the Oberstleutenant Boerner bot was used to bring Loki/Gragg into the Daemon's circle around halfway through and isn't mentioned again until some way into the sequel Freedom.
  • A regular event in the Harry Potter books.
    • One good example is basilisk venom. This is established in the second book to be a deadly and destructive substance. This property comes into play at the end of Chamber of Secrets when Harry uses a basilisk fang to destroy the magic diary. Five books later, Harry, Ron, and Hermione are desperate for a way to destroy the Horcruxes they've collected — and Ron goes down to the Chamber of Secrets and grabs an armful of basilisk fangs.
    • On that note, Godric Gryffindor's sword is a twofold Chekhov's Boomerang between its multiple reappearances and the fact that it's goblin-made and therefore "imbibes only that which strengthens [it]," when Harry used it to slay the basilisk, the sword absorbed the venom. Thus, Ron is later able to use the sword to destroy the locket Horcrux.
    • In Deathly Hallows, remember the passage early in the book where 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. 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 Moment of Awesome by the way. Now that's a Chekhov's Boomerang!
    • For that matter, Tom Riddle's diary is one as well — when it appeared in the second book it seemed like a mere MacGuffin for Harry to face Voldemort again. After it was destroyed, it seemed to have served its purpose and could be forgotten about like the Philosopher's Stone. And then in sixth book, Dumbledore explains about the Horcruxes and it's revealed that the diary was a major clue.
    • One that's only in the second book: Mr Weasley's flying car. Ron, Fred and George use it first to get Harry out of the Dursley's house when Uncle Vernon locks him up. Two chapters later, after missing the Hogwarts Express, Harry and Ron use the car to get to Hogwarts. Near the end of the book, Harry and Ron stumble across the car in the Forbidden Forest. After Aragog allows Harry and Ron to be eaten by the other spiders, Harry and Ron are rescued by the car, which gets them out of the Forest.
    • In Harry Potter and the Order of the Phoenix Zachariah Smith's comment about Expelliarmus not being useful against Voldemort is amusing, but it also counts as a boomerang, because in Deathly Hallows Harry's identity is revealed by the fact that Expelliarmus is his signature move.
    • Dumbledore's Chocolate Frog card is probably the oldest boomerang in Jo's arsenal; Harry reads it on his first train ride to Hogwarts, and uses it about halfway through the book to identify Nicholas Flamel. Nothing else on the card is useful until the very last book, when Dumbledore's duel against Grindelwald is brought up again as an important point.
    • Harry gets his invisibility cloak in the first book; it's used several times throughout the series, and seems to be a relatively mundane magical item. Until the final book, when the heroes learn that invisibility cloaks are unreliable and wear out over time... except for Harry's. It's strongly implied to be the mythical original invisibility cloak, supposedly created by Death himself, and the most prized of the three Deathly Hallows.
  • In Rhys Bowen's Heirs and Graces, Sissy's beautiful chiming clock is first significant because it runs slow. Then at the climax, Sissy saves Georgiana's life by throwing it at a would-be murderer.
  • The Hunger Games:
    • The nightlock berries that Peeta accidentally kills Foxface with come up again after 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.
    • Wiress and Beetee are known to be capable of making bombs, which helps out everyone in Catching Fire multiple times when they're able to manipulate the forcefield. Then, Beetee uses his skills in Mockingjay to kill many civilians.
    • The couple that Katniss sees on the edge of District 12 are a double between this and Chekhov's Gunman. One (Lavinia) shows up later in The Hunger Games, but the experience itself rebounds as an early clue that District 13 is still there, because they were escaping there.
  • Light And Dark The Awakening Of The Mageknight: One would think that the dagger given to Danny would only be used to locate other potential knights but it comes in handy not once but twice. Except the second time Danny realizes that it is not truly helpful.
  • In Mr. Standfast, Hannay is given a decoration to wear on his pocket watch to identify him to another British intelligence agent. They meet, look at each others' watches, and the story proceeds. Several chapters later, when Hannay is alone and in desperate straits, a complete stranger (also, it turns out, a British intelligence agent, in the area on unrelated business) notices his watch decoration and offers him assistance.
  • In Terry Pratchett's Nation, Mau leaves an axe in a tree in the opening scene. After a tsunami knocks the tree into the ocean, he paddles past it in a canoe and feels vaguely cheated when he can't pull the axe out. Then, in the final confrontation with the Big Bad, he's unarmed, desperate, and hiding behind a sunken log. Guess which log it turns out to be...
  • In Old Man's War: The Ghost Brigades, protagonist Jared Dirac discovers that his SmartBlood can be remotely instructed to spontaneously oxidize (i.e. combust), first observing this in training when it kills a mosquito that tries to drink from him. Later on, it saves his life when he blinds an enemy combatant by spitting SmartBlood into its eye-analogues and igniting it; then at the book's climax, when the Big Bad tries to perform a Grand Theft Me, Jared counters him by combusting all the SmartBlood in his body.
  • In Revelation Space, Sylveste has "hot-dust" implanted in his artificial eyes before being evicted from Resurgam into the hands of the Nostalgia for Infinity crew. In later conversations on the ship, Sylveste reveals that he had been bluffing about the hot-dust implant. But at the climax, when Sun Stealer is about to force Sylveste to expose humanity to the Inhibitors, Sylveste reveals that he was bluffing about bluffing, and activates the hot dust.
  • Matthew Reilly often re-uses plot devices. For example, in Scarecrow, Knight revealed he was able to track Gant on his Palm Pilot because he hit her with a cloud of transmitting microdots. He used the same trick to track down Schofield. Mother saw this, and used his Palm Pilot to track down Schofield again.
  • A Series of Unfortunate Events: In The Ersatz Elevator Violet attempts to use fire tongs for several different things, including welding and noisemakers. They only are effective for their final use, however.
  • Small Game introduces the crew's firearms for defense against a bear wandering nearby. The survivors manage to recover one and use it against the same bear. The weapon is used again against a survivor in a Mercy Kill.
  • After having been completely ignored since the second book, the Boxes of Orden become the key to the final resolution of the Sword of Truth series.
  • Tolkien's Legendarium:
    • There's an enormously potent boomerang thrown at the end of The Hobbit in the shape of Bilbo Baggins' magic ring, which has the handy property of making its wearer invisible — naturally a Chekhov's Gun, as Bilbo is able to take advantage of this fact on a couple of crucial occasions before the end of the story. But then the ring pops up again unexpectedly some years later in The Lord of the Rings.
    • Gollum is a living Chekhov's Boomerang. First, he (unintentionally) supplies Bilbo with the all-important Ring in The Hobbit. When he fully reappears in The Lord of the Rings, he leads Frodo and Sam into Mordor before betraying them to Shelob, leading to Frodo's capture and Sam's brief turn as Ringbearer. He disappears again after that, only to reappear just as Frodo reaches Mount Doom and decides to claim the Ring for himself instead of destroying it. Gollum attacks him and finally retakes the Ring, but during his victory dance, both he and the Ring end up toppling into the Fire.
  • Lizzie in The Underland Chronicles. In Gregor and The Code of Claw, her talent with puzzles becomes incredibly useful.
  • Sandy Mitchell's Warhammer 40,000 novel:
    • Ferik Jurgen, assistant to Commissar Ciaphas Cain, HERO OF THE IMPERIUM!. His unique status as a "blank" makes him impossibly useful and extremely effective, and at the most unusually convenient moments...
    • There's the good Commissar's skill with a chainsword and las pistol, as well as his "friendly" relationship with a certain Ordo Xenos Inquisitor.
  • In Warrior Cats, the fox trap from Sunset. First, Berrykit loses half his tail in it. Then later, it turns out to be instrumental to the villain's plot, and to beating the villain.
  • The Well of Moments features "detention specials", mini grenades disguised as used chewing gum. Jasmine uses them to escape the Basemen's trap, dealing particular damage to Mr. Who. Later in the book she uses them to evade Mr. Who alone after he splits off from the group. Then only two minutes later she uses one to leave a nasty surprise for Toshiro when he tries to steal the Well from her.
  • The Wheel of Time:
    • Callandor. It's the central MacGuffin of the third book, but soon after fulfilling prophecy by drawing it, Rand leaves it behind, and at the end of the fourth book he acquires the Choedan Kal, an even more powerful Amplifier Artifact. Callandor comes back in the eighth book, when he uses it against the Seanchan, and also gets used by another character during a key battle in the ninth, but it turns out to have a flaw that makes it seem too dangerous to use unless you're willing to let two women link with you. Then, over the next few books, it's noted how odd that Callandor is central to the prophecies but the Choedan Kal are not even mentioned, which leads Rand to destroy the male Choedan Kal. Ultimately, it's precisely the "flaw" in Callandor that makes it necessary; it allows Rand, Nynaeve, and Moiraine to hijack Moridin's link to the True Power and Hoist the Dark One by its own Petard.
    • The Bowl of the Winds is also a lesser example; it is a key plot point for much of books six and seven, is used to "fix" the weather in book 8, then mostly disappears. It makes a sudden reappearance in middle of the last book (14), being used to prevent the Dark One's evil weather from flooding the good guys to death.

    Live-Action TV 
  • The healing machine introduced near the end of Babylon 5's first season, and used 3 episodes later to revive Garibaldi. Then at the very end of the fourth season, someone uses it for a Heroic Sacrifice.
  • The Eye of Jupiter that turned out to be significant in Season 3 of Battlestar Galactica (2003) was originally just one of many random pieces of artwork actress Katee Sackhoff had painted on the wall of the set of Starbuck's apartment for the Caprica arc in Season 2. Which is kind of spooky if you think about it...
  • Breaking Bad has ricin. Walter created it early in Season 2 in order to kill his psycho boss Tuco. It comes back later in Season 4 when Walt attempts to do the same with Gus. In the series finale, Walt finally successfully uses it to kill Lydia.
  • One of the alternate names for this trope is from Buffy the Vampire Slayer. Olaf's Hammer was a hammer used by Anya's ex-husband, current troll god. It turned out to be the one thing the Scoobies had access to that could kick Hellgod ass.
    • Also, Xander's knowledge from turning into Military Guy came up more than once. Although by the second time, he didn't remember as much.
    • Buffy's rocket launcher turns up five years later for a Funny Background Event.
  • Midway through the Covert Affairs episode "What's the Frequency, Kenneth?", Annie, sneaking into an office at the Smithsonian, notices a trip alarm and doesn't trip it. So you just know she's going to trip it as she sneaks back out, which of course, she does; doors slam shut, the whole works. At the end of the episode, she's running away from the episode's main villain... and leads him right into the same room, wherein he trips the same alarm.
  • Criminal Minds The episode "L.D.S.K." establishes that Hotch keeps a backup gun in an ankle holster in the beginning of the episode; and sure enough this proves vital to stopping the killer at the end. The fact that he has a back up gun there would be important in sporadic episodes throughout the series, typically involving him having lost his first gun, and then grabing this one.
  • Doctor Who:
    • This trope was less common in the Classic series, but the Blue Crystal from Metebelis III is an exception, having played a major role in "The Green Death" and "Planet of the Spiders". Its return was particularly unexpected, as the Third Doctor had given it to Jo Grant as a parting gift when she was Put on a Bus at the end of the former episode.
      • And the Doctor keeps it around! He uses the crystal again in "Hide", eight regenerations later!
    • One very persistent boomerang, even banging back and forth between Torchwood and Doctor Who, is the Doctor's severed hand. After having been cut off the Doctor in "The Christmas Invasion", we see it in a jar for the entirety of the first season of Torchwood. At the end of the season it starts pulsating, alerting Jack the Doctor is near. Just when you think it has served its purpose, bringing Jack and the Doctor together in "Utopia", the Master steals it along with the TARDIS at the end of the very same episode and then proceeds to use to grab the Doctor's genetic code and age him in "The Sound of Drums" and then even further in "Last of the Time Lords". After the Doctor defeats the Master you think the damn thing is finally done with, but no, it's pointed out to Donna and Martha in "The Doctor's Daughter", and takes the Doctor's regeneration energy after he gets shot and creates a copy of the Doctor that goes on to live with Rose Tyler in "Journey's End".
    • In Series 6, the Teselecta robot, which is controlled by temporarily-miniaturised humans and which can impersonate anyone, has an episode devoted to it. In the series finale, it cameos briefly among several of the Doctor's friends and enemies while he's researching the Silence to find out why he has to die. That's it, right? No! The Doctor's dead body that burned in Episode 1 was a Teselecta set to look like him, controlled by a mini Doctor who was "barely singed". So the Doctor's not dead after all.
    • The Stasis Cubes in "The Day of the Doctor", used to capture a single moment in time to make Gallifreyan artwork (it's Bigger on the Inside). Okay, so the Zygons use it to get from England 1563 to 21st-century London. Used later with the Three Doctors when they need to get into the Black Archive to save Earth from nuclear warheads buried underneath the Archive. And just when you thought you'd forgotten about it again and it's used up all its ammo, the Doctors turn around and use it to save a freakin' planet!!
    • Midway through Series 3, we're introduced to the Chameleon Arch, a bit of technology which allows time lords can use to seal away their memories and live in human form. It shows up again in the series finale when the Master is found under the effects of one until regaining his memories. Then another Chameleon Arch shows up three regenerations and 9 seasons later in "Fugitive of the Judoon."
  • The pistol Dorothy finds in the trunk of the police car when she first lands on Oz in Emerald City. She tricks East into killing herself with it by the end of "The Beast Forever". It's brought back again in "Beautiful Wickedness" as the Wizard wants to reverse engineer it to kill the Beast Forever.
  • Father Ted uses this as a literal Brick Joke in the episode Speed 3, a ludicrous spoof where Dougal will be blown up if the milk float he's driving goes under 4mph. After a brainstorming session with other priests proves fruitless, Ted uses Father Jack's pet brick (which he tripped over earlier) to weigh down the accelerator allowing Dougal to escape. After the bomb goes off after colliding with the evil milkman, Ted is knocked out by the brick as it plunges down from the sky. Yes, it's that kind of show.
  • Hercules: The Legendary Journeys introduced the 'Hinds Blood Dagger', which had the power to kill Gods. The dagger served its purpose plot-wise, Callisto brutally murders the God Strife with it, and then Hercules literally rams it into the stone stair rail of the Temple of Ares. It later reappears on HTLJ's spin-off Xena: Warrior Princess, and is the object of at least four characters desires over the course of two episodes. It is later used to threaten Ares and gut God-Callisto before being 'disposed of' for good.
  • Ted from How I Met Your Mother, was established as knowing sign language (to conveniently help/hurt Barney's claim that he was his deaf brother). This casually came up later, when he spoke to his ex's deaf boyfriend.
  • Kamen Rider: Kamen Rider Blade threw a boomerang in 2005 and it didn't come back around until twelve years later in an entirely different series: Near the end of Blade it's revealed that if the Joker is the last Undead standing, the world will end; Kazuma Kenzaki manages to avert this by turning himself into a second Joker, putting the Battle Royale into a perpetual stalemate. Then in 2017 in the Kamen Rider Ex-Aid spin-off Kamen Sentai Gorider, Kuroto Dan enacts an elaborate plan to bring himself back to life, including an Unwinnable by Design virtual world which he oversees while disguised as Kenzaki, complete with copies of his powers. This attracts the real Kenzaki to the game world, who reveals that Dan screwed himself: since he's the only Undead around, the (game) world ends...and Dan's plot along with it.
    • Kamen Rider Zi-O: In the first part of the series, Sougo gains the powers of past Kamen Riders by giving them a blank Ridewatch in their year of origin, then returning to 2018 where the Watch has absorbed a fraction of their power, keeping it safe from the Another Riders. This aspect of the story is eventually dropped (Hand Waved as the result of alterations to the timeline), but in the penultimate episode Sougo travels to the year 2068, during his future self's attack on La Résistance that kicked off the events of the series, and secretly places a blank Ridewatch into Tsukuyomi's pocket. When he returns to 2019, the Watch has absorbed enough of her power that it becomes her own personal Ridewatch, letting her become an 11th-Hour Ranger.
  • Some plot elements from Lost might arguably fall into this category (although some fans will probably insist that everything on this show happens for a reason, and everything is planned out in advance). For example, in the Season 1 finale, Jack, Kate, Locke, and Hurley take several stacks of dynamite from the Black Rock and use some (but not all) of them to blow open the hatch which leades to the Swan station. In the Season 2 episode "Everybody Hates Hugo", Hurley wants to use the leftover dynamite to blow up the Swan's food storage Room, although Rose ultimately manages to change his mind. The dynamite is finally used by Mr. Eko and Charlie in the Season 2 finale, in a (futile) attempt to open the Swan's blast doors, which have been closed by Locke and Desmond to lock everyone else out.
    • Crazy to see this dynamite as an example of coming back out of nowhere one season later, given that it was again explored at the END of the series, when Richard planned on blowing up the plane.
    • The Dharma van in Season 3, which was originally the centerpiece of a filler episode. Most of the season went by without it appearing again, until it was shown in a flashback to be the place where Ben killed his father. Then, in the season finale, Hurley uses it to cause a distraction and save Sayid, Jin, and Bernard's lives.
  • My Name Is Earl: Kenny, the first person Earl made restitution to after creating his list, has been made use of for his computer skills and working at a copy place several times since then. Once he got Earl, Randy, Joy, and Darnell jobs in an office by taking the computer literacy test four times — once for each of them.
  • In one of the first few episodes of NCIS, it is established that Abby is fluent in sign language, since both of her parents are deaf. When she appears in the spinoff series NCIS: Los Angeles, she is kidnapped by a serial killer who streams live video of her online. He also gives her a paralytic that wears off gradually as the episode progresses, starting with her hands. As soon as she is able, she begins fingerspelling to the team, such as the fact that the door is booby-trapped. Luckily there's another signer on the team...
    • In one episode of NCIS, DiNozzo contracts pneumonic plague, though he's treated by the end of the episode. Seasons later, when Tony's car is blown up, Ducky's very sombre mood during the driver's autopsy turns to delight when he extracts a pair of perfectly healthy lungs - the plague would have left very obvious scarring. Whoever the unrecognizable driver was, it's not DiNozzo.
  • Power Rangers and Super Sentai:
    • Linkara recently pointed out the Zeo Crystal had been used like this in Mighty Morphin' Power Rangers in the transition to Power Rangers Zeo. It was first introduced mid-season as a plot device to drive the conflict between the heroes and villains for a couple of episodes, and, knowing Power Rangers, you would expect it never to be used again, but, at the end of the season/transition between series, it comes back as a way to restore the Power Rangers to their adult forms and give them new powers.
    • Unsurprisingly, Super Sentai has versions of this, since its footage is used for Power Rangers. Nearly every series has had a movie in theaters, and in recent years there has almost always been an exclusive powerup of some sort introduced, either for the rangers, their mecha, and sometimes both. They would then later be remembered by the rangers arbitrarily at some point later in the season and used only once, maybe twice before its end. (Sometimes after its end with the teamup movies) The only series so far with repeated use of the movie powerup in-series is Shinkenger's Kyoryuu Origami Disc.
      • Naturally, when some of these were translated to their respective American seasons, they ended up becoming Forgotten Phlebotinum instead. Though some of these were only used for finale arcs or teamups with explainations why they were unavailable before, justifying that status.
    • Power Rangers Time Force has the Electrobooster which is used for its function in the episode it is introduced, and then gets stored in the teams hideout where it comes back to play a part in the All Your Base Are Belong to Us finale.
  • Stargate SG-1 and its Spin-Off Stargate Atlantis have very long memories, with many items you'd filed under Forgotten Phlebotinum years ago coming back.
    • 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, used again in an Atlantis episode a few years after that, and finally becoming a fundamental plot device in Stargate Universe.
    • Another SG-1 example: the protagonists create a virus that will render a Stargate nonfunctional, and they use it on the Stargate of a planet owned by Ba'al. Demonstrating amazing knowledge of the Stargates' programming, he modifies it to spread throughout the whole Stargate network, shutting down every 'gate in the universe before they manage to reverse the effects. Then, a number of episodes later, they need to get an Ancient super-weapon working to wipe out the Replicators (who threaten to consume all matter in the galaxy), and it comes up that they need to figure out how to dial every Stargate in the galaxy simultaneously.
      Jacob/Selmak: I have no idea how to alter a Stargate to perform such a function. I don't know of anyone who can.
      Sam: I think I know someone.
    • Another is the Quantum Mirror from "There but for the Grace of God" it is used a few seasons later to introduce an alternate universe Carter and Kawalsky (killed off in the beginning of the series) for an episode. It is then referenced in Season 9 as a possible solution for a problem they had encountered, but it had been destroyed.
  • In Star Trek: The Next Generation, the Enterprise's use of the deflector as a weapon seemed pretty nifty, even if it didn't work. You didn't expect this to become a standard trick in every subsequent series.
    • A new shield enhancement that allowed a ship to fly into a star's corona was introduced as a mere plot device for a minor episode, but reappeared not long after in a major episode when they used it during a battle with the Borg.
  • In the pilot for Star Trek: Voyager, Neelix has his own ship. By the end of the episode he's joined the crew, and his ship is kept in the shuttle bay. His ship would go on the useful in a number of episodes throughout the series, when Voyager either couldn't be used, or its sensors were damaged but his weren't.
  • Ultra Series: The Magnerium Medicalizer was used by the Terrestrial Defense Force's Ultra Garrison to revive a crucified Ultraseven, and was not used again until over 30 years later to save Ultraman Mebius!

    Myths & Religion 
  • Classical Mythology: When Heracles slayed the Hydra, he dipped his arrows in its poisonous blood thinking that Someday This Will Come in Handy. 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.

  • When the Red Panda enlists in the army and joins the Home Team in the Red Panda Adventures, he discovers that the government has multiple secret files that contain his and the Flying Squirrel's secret identities. A running gag for a while is the Panda and Squirrel locating the copies and not only doctoring them to hide their identities, but altering each file differently, with progressively more outlandish backstories, such as one claiming the Red Panda was actually his own commanding officer, Colonel Fitzroy. This initially comes back when Fitzroy is gunned down as part of an attack on the Home Team superheroes' secret identities, and the Flying Squirrel uses the fact Fitzroy was a target at all to deduce the culprit was someone with access to the Home Team file. In later episodes, Canadian government officials make reference to the Red Panda and Flying Squirrel being a reformed mobster and his moll, revealing that the government still has the doctored files and thinks them genuine.

  • Opera — Verdi's "Rigoletto" (and the Victor Hugo play "Le Roi s'amuse" on which it is based, although in the court of a French King rather than an Italian Duke): a curse that strikes twice. At the denouement of Act 1, the curse is pronounced by Count Monterone, on the court jester Rigoletto, as revenge for the latter's part in (and subsequent mockery of) having provided Monterone's daughter to the Duke of Mantua as one of his many mistresses in debauched parties. At the end of Act 2, it is Rigoletto's own daughter Gilda who is carried off by the courtiers to be the Duke's next plaything, with Rigoletto tricked into helping them. The curse having now struck, Rigoletto believes the worst has happened: and witnessing Monterone being dragged off to jail, swears that he will be the instrument of the old man's revenge on the Duke (whom he also cursed). Rigoletto engages an assassin to murder the Duke on one of his incognito amorous adventures around town: however, the assassin's sister falls in love with the Duke, they agree to substitute another target — the next random stranger to knock on the door of their inn. The whole scene has been overheard by Gilda, who decides to die for her "lover" even though he has now spurned her, and knocks on the door herself. Rigoletto, coming back for the body, discovers his daughter dying, and realises that Monterone's curse has struck for a second time. (Meanwhile, the Duke gets off scot-free, so much so that he never even so much as learns there was an assassination attempt against him, and the assassins never even learn that their intended target was the Duke...)

    Video Games 
  • In Avernum 2 and 3, you get an ability called "Ritual of Sanctification" for a specific quest in each game. (It's used to purify an evil altar.) You can use it several more times throughout each game, and at least once it's needed to complete another quest.
  • The Bizarre Adventures of Woodruff and the Schnibble: The chewing gum, which is required twice (the second one at the end of the game).
  • In Bloodborne, a young girl gives you a tiny music box so her parents can recognize its tune. The song causes Father Gascoigne to clutch his head in pain as its melody briefly restores his memory during the fight against him. When you get to Mergo's Wet Nurse, the background music "Lullaby for Mergo" turns out to be the same song that the music box plays. Using the tiny music box on the Wet Nurse also causes her to strafe as if dodging an attack. And at the end when Mergo is crying for the Wet Nurse shortly after she died, you can play the lullaby with your music box to make Mergo laugh for the last time.
  • In A Boy and His Blob (the original), the Apple Jack jellybean is used to lift off the manhole cover and escape from the sewer. It's used again at the very end of the game to defeat the emperor.
  • Broken Sword: Shadow of the Templars has the manhole-opening tool.
  • Chrono Cross. Oh, Chrono Cross. There are party characters that serve this purpose.
    • Before that, Melchior in Chrono Trigger is an example of this with a Chekhov's Gunman: He first appears to just be some random merchant, then it turns out he's the forger of the Masamune, and then he turns out to also be one of the three gurus of the ancient age of magic.
  • In Chapter 1 of Deltarune, Lancer makes you build "A Machine to Thrash Your Own Ass", where you can customize its features. It shows up a minute later, but shoddily made, and Lancer ends up destroying it without a fight. Then in Chapter 2, the machine shows up again, this time being properly built and serving as a weapon Rouxls Kaard uses against you. Then it shows up a third time, as part of the Humongous Mecha you construct to fight off Giga Queen in the climax.
  • The Dig has a shovel serve as the puzzle solution 10 separate times. At one point the main character even comments, "What if I hadn't brought this shovel along? No, that's not worth thinking about."
  • Discworld II: Everything from the pot of glue through the art of beekeeping to the continual theft of stuff from Mrs. Cake's house.
  • Dragon Age II: The red lyrium idol Hawke and Varric steal from the Primeval Thaig in Act 1 glows ominously as Varric's brother Bartrand locks them into the thaig to die. It shows up again in Act 2 where losing it has now driven Bartrand insane and again in Act 3 where finding it has driven Meredith more insane.
  • Dragon Quest VII has a couple examples.
    • Early on in your quest, you meet the Fortune Teller Pamela, and help her out when her Cassandra Truth falls on deaf ears. After several adventures, you abruptly learn she has the knowledge required to fix another problem you've run into: curing a victim dosed twice by the Gray Rain, which is in and of itself a bit of a Boomerang.
    • The best example, however, is the Empty Bottle you obtain after using the Holy Water. This sits in your inventory after its first use and is easily forgotten, until you need to use it to collect some other special water. Notably, you can do this long before finding out it's required.
  • Dragon Quest VI has a few as well:
    • The Dream Dew. Used to allow people from the "upper"note  world, like The Hero, to be visible to people in the "middle" world. You and your Boisterous Bruiser friend are not the only ones that need it...
    • The franchise-famous Mirror of Ra is needed to expose Murdaw's deceptions as well as trigger a later quest involving a mirror prison.
    • A more innocuous one is the golden pickaxe: used to break up rocks in a mountain cave and some floorboards guarding an Armor of Plot Advancement.
  • Paula's Pray ability in EarthBound (1994) starts as a useful, if unpredictable skill, that takes a back seat to her more reliable psychic powers. Then you need to pray for a chance of beating the final boss.
  • The Elder Scrolls V: Skyrim requires you to use an Elder Scroll to learn the one Shout that will allow you to defeat Alduin by time-traveling back to when the Shout in question was invented. Once you're done with it, you can (optionally) haul it up to the College of Winterhold and sell it to Urag gro-Shub for a nice price. Then the Dawnguard DLC comes around, and have fun trying to get your Elder Scroll back...
  • Final Fantasy IV: When Cecil becomes a Paladin, he receives the Legend Sword (SNES version). You find a number of more powerful swords as you progress through the game, but if you can acquire the Adamant ore and take it to a certain blacksmith, he'll temper the sword and make it into the more powerful Excalibur.
  • In Final Fantasy VII Remake, when Cloud falls from the Sector 5 reactor into Aerith's church, he uses a Grappling-Hook Pistol in a somewhat successful attempt to arrest his fall (this also serves to explain how he survived falling from such a height, something the original game glossed over). When Shinra attacks the Sector 7 support pillar, Wedge gets knocked off the tower...but then uses the same kind of grapple gun to catch himself, which keeps him from dying as per the original. Shortly thereafter, Leslie Kyle gives Avalanche several souped-up grapple guns so they can climb up to the plate and infiltrate the Shinra Building.
  • Full Throttle does this. It's a game about a Genius Bruiser biker. The extremely useful item in question? A tire iron.
    • It might even go so far as to be Chekhov's Yo-Yo. You use it, then again, then again, then again, then again...
  • God of War has Pandora's Box
  • In Grim Fandango it's very easy at times to forget you have a scythe.
    • Grim Fandango has so many guns lined up on its narrative mantelpiece that it probably crosses the line into Chekhov's Armoury. At least one is actually a boomerang: Near the start of the game, the player learns of the two strange properties of the DOD's packing foam, and not too much later, uses one of them (that it expands like crazy when the two types are mixed.) Hours and hours later, nearing the end of the game, the player needs to remember the other property: that it combusts if sprayed by a certain type of chemical fire extinguisher.
    • Another boomerang can be launched in Year 2 by examining a cabinet in Toto Santos's scrimshaw parlor, which causes Toto to note that he should remember to restock liquid nitrogen. In Year 4, Manny steals a bottle of the chemical from Toto in order to freeze the gelatin covering a booby trap (long story). After that, near the very end of the game Manny uses what remained in the bottle to get rid of the flower on his chest after getting shot with a sproutella dart. Toto does specifically mention that he uses the stuff as a pain killer...
    • Glottis's capability of drinking entire barrels of (preferably alcoholic) beverages, also introduced in Year 2 and already used shortly after its introduction, comes back as a part of the abovementioned boobytrap puzzle. Glottis hangs a lampshade on this, complaining that his stomach doesn't stretch like it used to back then.
  • Halo: In Halo: Combat Evolved, the Master Chief has to get the Index to activate the ring and destroy the Flood. In the very last moment Cortana takes the Index away in order to prevent Chief from accidentally destroying the entire galaxy. In the end of Halo 3, the Flood has taken control of the Ark, a massive space station far outside the galaxy that serves as the control room for all the Halos in the galaxy and creates new rings if any are destroyed. With an almost completed ring already inside the station, the only thing needed for it to destroy the Flood would be an Index to activate it. "I'm a thief... but I keep what I steal."
  • In Hitman: Blood Money, at one point you have to use a death serum to rescue a fellow agent by faking his death. In the final mission you use it again to fake your own death in order to kill the true Big Bad behind the whole plot against you.
  • In Jurassic Park: The Game, Sorkin activates one of the tour cars for Gerry, Jess, and Nima to use when they need to get to the Visitor Centre. After a long confrontation with the T. rex, Gerry then gets her to activate it again, distracting the giant predator with the movement and luring it away. It doesn't reappear until episode four, when it turns up and takes Gerry and Nima to the marine exhibit.
  • In Kathy Rain, the disk the titular character recives for hacking passwords from the local hacker, Dave, comes in handy one more than once. As does her stun gun.
  • The Legend of Zelda:
    • The Legend of Zelda: The Minish Cap: The Cane of Pacci. 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 in order to beat the Final Boss.
    • The Legend of Zelda: 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 later comes into play when Link is climbing Death Mountain (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, 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 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.
  • This goes all the way back to 8-bit videogames: in the Gargoyle Games' graphic adventure Marsport, one puzzle involves baking a cake. A later puzzle apparently involves baking another cake — but this turns out to be no longer possible. It transpires that the real solution to the second puzzle is to just use the same cake as before.
  • Mega Man:
    • In Mega Man 2, the Bubble Lead is pretty much useless against every other enemy in the game... until you get to Wily's Hologram, in which it's the only weapon that causes actual damage to it instead of healing it to full like every other weapon.
    • In Mega Man 3, the Top Spin is used once against a boss like all the other weapons, and then, it being the worst attack in the history of Mega Man, you probably never use it again...which is a shame, because the final boss goes down with one hit of it.
    • The Rolling Shield from Mega Man X is a bit unwieldy in regular gameplay, but it's the only special weapon that can damage Sigma's second form. Otherwise, you're stuck with charged X-Buster shots.
  • In Mega Man Star Force:
    • 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.
    • Then there's the third game with Magnes' rocket. Launching it is the main objective of Echo Ridge Elementary's Science Club, and Luna 4 Prez gets caught up in it to secure votes for Luna. Once it gets launched, players tend to forget about it until the very end — where the same incident that almost caused the rocket to explode gave it the Noise resistance it needs to get close enough to Meteor G for Mega Man to jump from WAZA's Dynamic Station through the rocket into the Meteor Server.
  • In Metal Gear Solid 3: Snake Eater, 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 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.
  • Monkey Island: Rule of thumb: If you're taught how to make one of something, you're gonna need at least two of it. Second rule of thumb: If an item doesn't disappear from your inventory after using it in an obvious way, you're going to have to use it later in a non-obvious way. Some examples:
  • In My Ex-Boyfriend is a Space Tyrant, this happens with the Sonic Spanner. It is the second item in the entire game that you pick up and you use it twice. Once on the stuck door right next to the toolbox where you found it and 10 minutes before the game is done to combine it with the oxygen tank and harness to make a jetpack with which you can see your ex-boyfriend.
  • In Neoquest II, an RPG in Neopets, the sword you start off with is also the best sword to use against the final boss.
  • The Sword of Gith in Neverwinter Nights 2 is the only weapon that can kill the King of Shadows, the Big Bad of the first campaign. In the second campaign, it is also the key to the Betrayer's Gate.
  • Goldbob in the second Paper Mario game qualifies. After first appearing as a spectator in the Glitz Pit of no apparent importance, he and his family are fellow passengers on a train to Poshley Heights, where an incident surrounding the family serves as a Broken Bridge sequence. Later in the game, Mario is told that Goldbob has some sort of importance in a Bob-omb colony in the frigid wastelands and needs Goldbob's permission to use a special cannon.
  • Done twice in Portal. First, at the end of the Companion Cube level, you have to throw your Weighted Companion Cube into the Aperture Science Emergency Intelligence Incinerator to finish the level. Then, near the end of the game, one puzzle requires you to manipulate a rocket-launching turret into breaking glass. Both the incinerator and turret appear a second time in the final boss room and are crucial to winning the battle.
  • Portal 2: 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. Near the end of the game, Wheatley sets up an obvious death trap... full of defective turrets.
  • In Project × Zone after the prologue and you're on the first chapter, while Kogoro and Mii discuss on what their next move will be, Chun-li and Morrigan come out of the fountain after their escapades in the fifth prologue. For quite awhile, you don't get to visit the Koryuujii estate until much later when Oros Prox invades Mii's home. A few chapters after that when the party decides to return to said estate, it turns out there's an underground passage located underneath the fountain. It turns out it's the Oros Prox's base of operations.
  • The Enchanted Key in Runescape. It's given to you in Making History in order to find a chest. It then comes back to prominence in Meeting History and The Light Within, each subsequent quest revealing it to be more important than the previous.
  • Shantae and the Pirate's Curse: The Palace Disruptor Cannon is first used to accidentally open a path into the last Den of Evil and apparently incapacitated for the rest of the game when a component needs to be replaced before it could be fired properly only for it to return at the end of the game during the battle against the True Final Boss when Risky hijacks it and uses it to help Shantae blow the Pirate Master up to kingdom come.
  • Sonic Adventure 2:
    • The Mystic Melodies seem useless after doing the lost Chao missions, but some Hard Level missions require them for advancement.
    • Also required in one case to get another upgrade. In fact, Security Hall almost seems like an aversion of the "You need the Mystic Melody to get the Lost Chao" rule until you remember that you needed the Mystic Melody to get the Treasure Scope, found in that very level, which was necessary to get the Lost Chao.
  • Strong Bad's Cool Game for Attractive People: In the last part of the game, "8-Bit is Enough," you use a key to open the arcade cabinet towards the very beginning of the game. At the end, in the final dungeon of the mainframe after beating Ultimate Trogdor, you are faced with a locked door as the dungeon crumbles around you. Guess which key opens it.
  • In Suikoden V, you first use the sluice gates at the ruins near your castle to break out a flood to destroy the Godwin dam and bring back water to Lordlake. After awhile you seemingly forget it because of a series of events, including abandoning your castle from your enemies, until Lucretia tells you to go back to the ruins and open up the sluice gates again to flood the caste.
  • In Uncharted 2: Among Thieves, Nathan Drake finds an oil lamp made of a combustible resin, used to uncover a hidden map. This resin becomes important later on when it is realized to be the the sap of the Tree of Life and is subsequently used to defeat the Final Boss through its combustible properties.
  • The birdseed in the third episode of Wallace & Gromit's Grand Adventures is used for 3 separate puzzles.
  • In Wild ARMs Cecelia's Tear Drop item comes back several times.
  • In Ys Ancient Ys Vanished Omen, you can sell a Gold Pedestal to Pim. In Ys IV: Mask of the Sun, you buy it back from him to raise the Ancient City.

    Visual Novels 
  • Numerous pieces of evidence in the Ace Attorney games show up in multiple contexts in the same case, or even pop up in multiple cases as Call Backs or Continuity Nods.
    • The Thinker Statue is used as the murder weapon in both case 1 and 2 of the first game. Also the fact that the statue is secretly a clock comes up in both cases as well (you nail two criminals when they admit it was a clock even though they shouldn't know).
    • The metal detector from game 1, case 4, which is originally used just to gather other evidence but makes a triumphant comeback in the courtroom, helping to finally nail the real culprit. Then it comes back in Phoenix Wright: Ace Attorney – Trials and Tribulations case 5 when you use it to find the real murder weapon.
    • The fact that a person's appearance changes during a channeling. You see it for the first time in the first game, and becomes crucial both in the second and third installments.
    • Trucy's panties — fake prop bloomers, not her actual underwear — are used to object to testimony in the second case of Apollo Justice at least 3 times; first to show proof of other crimes on the same night, then to show what the college student witness was hiding, and then, at the very end of the case, to prove why the car couldn't have been used to transport the body. The judge even comments on Apollo's repeated presentation of that piece of evidence.
    • The Case 4 knife in Ace Attorney Investigations: Miles Edgeworth. At first, it seems to be only significant because of its status as a murder weapon, but before the end of the case it's revealed to be doubling as a missing piece of evidence, the Yagatarasu's Key. Shortly after, it's stolen by the murderer, who escapes. End of the story, right? Wrong. It shows up again in Case 5 (seven years later), in the possession of that case's first murder victim, Manny Coachen. The full significance of the item is eventually revealed: the key end opens the safe in his office, while the "knife" portion is used as a secondary key to open a secret compartment in the safe. But we're still not done; later on, when the murderer — Quercus Alba — is being confronted by Edgeworth, it comes to light that he likely struggled with Manny Coachen, and Manny fought back with a sharp stabbing weapon of some kind — one that had somehow been concealed in a way to avoid detection. Guess how Manny pulled it off. That's right, he used the Yagatarasu's Key as a knife, as his compatriot had done seven years before.
  • In Fate/stay night, this occurs with Caster's Noble Phantasm Rule Breaker. First used in the Fate scenario to control Saber (thus leading to a Dead End). Then in Unlimited Blade Works used in Archer to break his contract with Rin, letting him fight Shiro and then again in Heaven's Feel, long after its owner's death, it's traced by Shiro to break Sakura's connection with Angra Mainyu.
  • Snake's prosthetic left arm in Nine Hours, Nine Persons, Nine Doors. It's first mentioned as Foreshadowing in Door 8 by Clover (not on every route, though). It doesn't serve its first purpose in the plot until June and Junpei return to Door 3 in the Safe ending and Junpei realizes that the corpse who they had assumed was Snake's has an ulna in his left arm, which is impossible, leading him to conclude that Snake is still alive. It then comes up again later in the Safe ending, when Seven and Junpei want to cross Door 9 with the aid of the O bracelet they found (which functions like it's a 6, allowing their digital root to be 9). Snake crushes his fake arm and gets rid of it along with his bracelet so he can cross the door too without blowing up. This Loophole Abuse was his last resort, his trump card, all along.
  • In the first main game of Your Turn to Die, two sheets of paper containing the names and occupations of some of the participants as well as some percentages on the left brews a conflict within the group when Sara is erroneously listed as a murderer. The conflict is resolved with the reveal that Gonbee Yamada is actually Alice Yabusame as well as the murderer listed on the roster. In the second main game, the papers become a central element in exposing Gashu's transgression, as well as revealing Sou's true identity. He ends up revealing that the percentages are the victory rates of the candidates of the death game. They are re-introduced once again in Chapter 3 Part 1 where Midori reveals that the purpose of calculating the percentages was to give certain people "helpers" and "handicaps" in an effort to make everyone's victory chances equal, and is why Joe, Nao, and Kugie were roped into the death game.

    Web Animation 
  • Not to forget Tucker's Sword in Red vs. Blue. First it's a sword, then it's a key. And when you think they are just going to use it like a sword some more, there are two other instances of them needing to use it as a key!
  • An early joke in RWBY involves each student of Beacon Academy being assigned rocket-propelled lockers to store their weapons and Jaune getting tossed into one of them by a local bully and launched off to god knows where. In the next volume, it's shown that they can be used to quickly acquire one's weapons in case of emergency. When Ruby notices something fishy going on at a communications tower, she walks straight out of the dance party and calls her locker (which leaves a crater on the ground as it lands, by the way) with her Crescent Rose inside. In volume three the lockers make a comeback during a battle, used by all of the students to get their respective weapons, as well as lockers themselves being used as weapons to strike down a giant monster bird. The same episode involves yet another use of these lockers: Ruby launches one of them towards an airship and flies on it to quickly reach said ship. Thought Rooster Teeth ran out of ideas on how to use them? In the volume three finale we learn the real reason behind the initial Chekhov's Gag: It's established that a person may be stuffed into the locker and launched off to somewhere else without any real harm. Which is exacly what Pyrrha does to him to make sure that he's safe and that he won't stop her from facing Cinder.

  • In Flying Man and Friends, the main characters move into a house they "found" early on in the series. Five months later, the comic finally addresses who the house originally belonged to (a platypus named Platy).
  • Girl Genius:
  • When they're not Brick Jokes, Homestuck is full of elements that are used and then unexpectedly get reused later. This even applies to characters.
  • Jungle Juice: The chainsaw, initially brought out by Jun Ji on the first day of class for a very extreme game of tag, later gets stolen by Hyeseong in order for Suchan to be able to fight the mantis. Suchan manages to cut off one of his bladed forelimbs with it, only for it to stop running, and the Mantis breaks the chain on it with his one good arm, and that's the last we see of it... Until it reappears over sixty chapters later wielded by Huijin! It turns out that she grabbed it from Jun Ji's office, and uses it to cut off the Exploding Ant Predator's detonator arm.
  • The Order of the Stick:
    • Belkar acquires a Ring of Jumping. This first allows him to escape his cell in Azure City, then later he lends it to Roy, who uses it to jump on the back of a flying dragon and fight the Big Bad. And get himself pointlessly killed.
    • After being mocked for having Intelligence when it doesn't have a direct effect on a Fighter's combat ability, Roy shows off the perks when his knowledge of architecture (thanks to having both the stat and cross-class skill ranks) to collapse a ceiling on his opponent. Later, that same knowledge of architecture allows him to identify the fact that a pillar isn't load-bearing and thus is most likely hiding something.
  • While Pete Abrams of Sluggy Freelance seems positively Crazy-Prepared with all those Chekhov's Guns he has hidden all over the place, we can safely say he certainly didn't plan the part about the man who sold Bun-bun to Torg in the first place and who was shown in one panel talking on the phone and saying there would be no refunds. Nine years later it's revealed that he was actually the supernatural being known as Uncle Time, as Bun-bun's ending in Torg's "possession" was shown as the culmination of a story involving rather convoluted time travel elements. Even the squiggle on his shirt gained significance.

    Web Original 
  • The Whateley Universe authors love Chekhov's Gun and foreshadowing enough that this is getting pretty common. The way a blackmailer got a note past magical wards and into Poe Dorm comes back later as the way someone gets a tracker in Fey's luggage so she can get ambushed at Christmas. The Hawthorne girl in a Carmilla story who has toxic blood? She turns out to be Phase's cousin, who shouldn't even have mutant powers. Or the way that Counterpoint's power mimic ability works. Or Phase's little trick stealing Generator's underwear while she is wearing it keeps coming back. There's a ton of them.

    Web Videos 
  • In Noob Sparadrap's hacked staff is one. He got it in Season 1, the fact it's overpowered and a present from Tenshirock is discovered in Season 2, at the end of which it gets Brought Down to Normal. In Season 4 finale, Tenshirock reactivates the plan that made the staff overpowered, right around the time Sparadrap ends up fighting someone against whom he probably wouldn't stand a chance with the staff in "normal" state. Something similar happens in Season 5 finale.
  • Used several times throughout Stampy's Lovely World, 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 help with the building of the Soggy Sandwich restaurant. Then it's used again in Episode 184, "Clone Calamity", where HitTheTarget makes a Clone Army and 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, 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 Zerg Rush 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.

    Western Animation 
  • Avatar: The Last Airbender:
    • Zuko's broadswords in Avatar: The Last Airbender. Most viewers are under the impression that the gun was on the mantelpiece (literally), it was used once, and that was that. But he ended up using it almost as much as firebending and it changed the course of the series many times.
    • Katara's necklace also qualifies. After Zuko ends up with it, and he unsuccessfully tries to use it to force Katara into helping him, you think its purpose is over. Then they reach the Northern Water Tribe, and its real point in the story arc shows itself.
    • Aang's bison whistle. In the episode where Aang buys it, it initially seems to be useless, but at the end it successfully summons Appa. Aang also uses it to try and unsuccessfully call Appa when he was kidnapped, and to round up some escaped zoo animals in a later episode.
    • And then there's Sokka's actual boomerang. It makes repeated appearances throughout the show, usually for comedic purposes... then it makes one final emotionally-charged appearance in the show's finale, just when you were least expecting it.
    • There's also the Waterbending Scroll. Obtaining it is the source of conflict for one episode, then it can be assumed that any gains Aang and Katara make in their waterbending from then until they reach the Northern Water Tribe can be attributed to the scroll. You wouldn't expect it to serve any purpose after that, but it does show up one more time, as an offering to Wan Shi Tong when he asks for a contribution to his library.
    • In an early episode, Iroh is found and arrested by Earth Kingdom soldiers while taking a bath, but as he's being led to a prison, he stealthily drops one of his sandals, which allows Zuko to realize he's been captured, allowing him track his uncle down and rescue him. You'd think that's it, but in the second part of the series finale, it's revealed Zuko kept the sandal on him ever since then, and he uses it to track down Iroh again to make amends.
  • Batman Beyond:
    • In an episode of Batman Beyond, one of Mr. Freeze's ice ray guns comes in handy against a villain who can turn into liquid.
    • Old man Wayne actually pulls useful equipment from his gallery several times, such as his old utility belt when the current Batsuit gets corrupted, or the Grey Ghost's hat and goggles when he needs to hide his identity. It's awesome.
  • This is a common usage in Danny Phantom. Nearly every Fenton invention will be used at least twice in the show, especially if it's unexpected. Special bonus points for one of the weapons for being an actual boomerang!
  • In an episode of Dexter's Laboratory where Dexter has to combat an alien life form that's possessed all his family members, he uses one of his self-manned robot inventions that he used previously to combat a group of bullies harassing him with dodge-balls even stating "I haven't used this baby since that whole dodge-ball incident".
  • A lot of the stories in Donald Duck & Co. works with a Chekhov's Boomerang returning in the end and solving the plot.
  • The Fairly Oddparents: Timmy Turner uses his magical time-traveling scooter several times during the series. He also sometimes uses other magical items more than once. (Including some that exploded two episodes earlier like the Shrinking Robosuit, but who cares...)
  • Futurama:
    • Torgo's Executive Powder from Futurama. It's got a million and one uses.
    • And again more recently with Professor Farnsworth's "Disintegration" (actually teleportation) Ray.
    • In "Leela's Homeworld", the professor's nose-making machine is later used to translate the message that was with Leela when she was abandoned as an infant.
      Fry: "Isn't that the machine that makes noses?"
      Professor Farnsworth: "It can do other things. Why shouldn't it?"
  • The Talismans in Jackie Chan Adventures pop up several times after the first season.
  • My Little Pony: Friendship Is Magic: Pinkie's "Pinkie Sense" returning in Season 2's "The Mysterious Mare-Do-Well" and "It's About Time" from Season 1's "Feeling Pinkie Keen".
  • The The Owl House 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 Hunter when the latter starts having a panic attack, and Hunter's knowledge of the exercise helps convince Willow that he's on their side. In the climax of the episode, Hunter tries to guide Gus through it when Gus goes into Heroic BSoD, 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, snapping him out of it.
  • The Phineas and Ferb episode 'Primal Perry' has a literal example, in Natasha, the giant boomerang used by the villain of the episode. About halfway through the episode, Natasha is thrown at Perry and flies off into the distance, and near the end of the episode, it destroys Phineas and Ferb's device of the day, before coming back again to further inconvenience Perry.
  • The third and final part of Regular Show's Grand Finale has Mordecai and Rigby use The Power, the magical keyboard from the show's first episode of the same name, to return to the final battle when they realize they've been returned to the start of the show. This episode is even called "The Power" to reflect this.
  • An episode of The Simpsons has Marge buying an impossibly absorbent paper towel brand and becoming enamored with its mascot. This seems to be just a setup for Homer and Bart to pull a prank on her, and apologize by going to a magic show that uncovers repressed memories of Homer finding a corpse in a quarry when he was a kid, but she then used the towels to drain the quarry of water so they can find the body.
  • The second episode of Sonic Boom has Eggman's kazoo, which he uses during the board game. Later, while Eggman's mech attacks the lair, Eggman uses said kazoo to wake up Sonic and Tails to activate the two killswitches at the same time.
  • South Park:
    • In the episode "Crippled Summer", after repeated failures to sabotage Jimmy's team, Nathan (the leader of the rival team) attempts to rig Jimmy's ukulele to explode, but it ends up used as an Xylophone Gag (since Nathan's plotline is a Deconstructive Parody of Looney Tunes). After the ukulele blows up in Nathan's face, everything involved in Nathan's previous plans come back to attack him again — a black mamba snake bites him, Tardicaca Indians shoot him with arrows, and a Tardicaca shark rapes him.
    • In the Episode "200," every celebrity/famous figure that has been on South Park is back in this episode. Tom Cruise, Barbara/Mecha Streisand, Mel Gibson, Bono, Paris Hilton, R. Kelly, Sally Struthers, you get the point. They're ALL back to sue the town..
  • Super Robot Monkey Team Hyperforce Go! has the "Pit of Doom". The first time it becomes important after its introduction (in Season 1) is when it becomes the location of Mandarin's cloning factory in Season 2. But in the Season 2 finale, it's revealed that Skeleton King's real intention for building it all along was to reach the egg of the Dark One embedded inside Shuggazoom to awaken it, hatch it, and unleash it on the rest of the universe. And at the end of Season 4 it becomes the place where Skeleton King is resurrected.
  • Occurs several times in TMNT 2k3, most notably in the episode "Same as it Never Was" in which the Turtle Tunneler, which had been introduced in the previous season as part of a different subplot, is used to kill an alternate version of the Shredder.
  • In Teenage Mutant Ninja Turtles (2012), we see that Baxter has collected a lot of mutagen in a giant vat in his lab. By the end of the episode, someone (Dogpound) falls in. In two later episodes, we see he still has it, and in each case, another character (April and Karai) falls in as well.

Alternative Title(s): Olafs Hammer