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 and Manga
- In Heroman Joey activates Heroman's Augment ability in Episode 4. Fast-forward 19 episodes later, and it is used to spectacular effect.
- 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!
- Well, not completely true: There were a few characters in the 2003 anime version that never appeared again, but they were just in Filler episodes. And even then, some of them still have a (slight) impact on the plot.
- 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.
- Pokémon Special manga. Bloody hell.
- 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" 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.
- In ×××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?
- 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.
- Mahou Sensei Negima! 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.
- 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.
- Naruto: Shisui Uchiha is a man who is mentioned to have died off-screen and only seems to have existed to explain who Itachi killed to get his Mangekyo Sharingan. 237 chapters later it turns out that the Sharingan Danzo has is from his body.
- Shisui returns again when Itachi breaks Kabuto's Edo Tensei Mind Control with his other eye.
- On a similar note, another things from that same story arc (the tablet hidden in the Naka shrine only readable with a Sharingan, containing the reason for the the Uchiha clan's creation) had it's secret (the clan was created to control the Nine-Tailed Fox) revealed... only for there to be even more to it even later! Turns out, a Mangekyo Sharingan and a Rinnegan reveal even more, namely the full tale of the Sage of Sixth Paths and all of the Tailed Beasts.
- It's also happened with techniques: the Shadow Shuriken technique was used once in the first story arc, but ended up being used again over 350 chapters later when Sasuke is fighting Itachi (which was also rigged to split apart sending the pieces everywhere), and then nearly another 50 chapters later, except Naruto was doing with a Rasenshuriken against Pain.
- Orochimaru's experiment to transfer the First Hokage's DNA into people to reproduce his Green Thumb? Yeah... turns out Yamato wasn't the only one who got it and lived ever.
- And Orochimaru wasn't the first person to try using the First's DNA.
- Naruto's Rasenshuriken was initially a melee attack, and it also had another drawback in that his hand would take a significant damage while using it. About 100 chapters later, it appears again, but it is now a projectile attack. Although it is not explicitly mentioned, it also has a limitation in that it is wasted if it misses the target or the opponent dodges it. About another 100 chapters later, it appears again and now it is a remote-controlled projectile.
- Impure World Resurrection has got to be the best example of this in Naruto. It was first used by Orochimaru to revive the first and second Hokages, and it didn't show up again for over three hundred chapters!
- In the arc where he first appears, Sai refers to a dead brother. This is commented on quite a bit, showing Sai's lack of emotion and artistic ability. Much, much, much later, this turns out to be his Berserk Button, which is pressed by Kabuto in two ways.
- One Piece does this frequently with some of the Loads and Loads of Characters (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.
- Monster - Johann's candy, the story books, Three Frogs, and many others.
- 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.
- 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.
- Shortly after the end of her arc we find out that Erza, who we saw in an earlier chapter of Fairy Tail loosing 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.
- 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.
- 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 Striker(s), 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.
- Lancia's Ring in Katekyo Hitman Reborn!!. 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.
- The Lagann Impact in 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 it's 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 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.
- Gundam00: 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 one). They also have to fall back on this strategy quickly after speculating on the risk. During the final episode (of season two), 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.
- In Zero no Tsukaima, 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.
- 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.
- 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).
- The Spirit Egg in the anime version of YuYu Hakusho.
- 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.
- In Haiyore! Nyarko-san, 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.
- In Pre Crisis Superman comics, a minor Silver Age story involved Superman gathering kryptonite from around the world, forming it into a small island in the ocean (there were a lot of kryptonite meteorites in those days!), and then propelling the whole thing into outer space to get rid of it. Still, it was the Silver Age, so kryptonite kept turning up on Earth despite this. Years later, DC Comics decided to stop using kryptonite as an easy plot device, so they had a freak accident destroy all the kryptonite on Earth, and the Superman comics went for a while with no (or at least fewer) stories involving the stuff. Writers missed it though, so years after that, they had the long-forgotten "Superman Island" of kryptonite return from space and scatter the stuff all over the world again.
- 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.
- Actually used twice. The "Blackest Night" Prophecy was also used in the early 1990's when the Green Lantern Corps was destroyed for the first time, after when Hal Jordan went mad with grief and became Parallax. "Blackest Night" was also the title of one of the comics leading to the end of that same arc, implying that Parallax/Jordan caused the Blackest Night. The Universe has since been rebooted and the prophecy retconned, however, so it's likely that in canon the first occurrence was just a warm-up.
- The first one didn't include Sodam Yat or Ranxx the Sentient City, both mentioned in the original Alan Moore story.
- 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.
- In Sonic the Hedgehog, 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 universe, setting the stage for the two franchises' crossover.
- Transmetropolitan: I-Pollen Damage, Source Gas and Spider's second back-up gun.
- 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.
- Despicable Me. Anti-gravity serum + minion. Hilarity Ensues.
- Despicable Me 2 has the memorable lipstick taser.
- 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.
Film -Live Action
- 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.
- In 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.
- 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.
- 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.
- 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 the book 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 Crowning 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.
- 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.
- 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.
- 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...
- 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.
- 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, but it turns out to be too dangerous to use, so he puts it aside again. 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 it, and it's increasingly clear that Rand and two women must use it in the Last Battle.
- 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.
- 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.
- 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.
- 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.
Live Action TV
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- The new Doctor Who uses this trope regularly, often to set up a dramatic scene for the season finale by introducing a concept earlier in the season.
- The two parter "Human Nature"/"Family of Blood" hinges on The Doctor's Time Lord self being concealed in a fob-watch. This reappears a few episodes later in "Utopia."
- 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 the moment 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".
- And 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.
- 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...
- 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.
- The Eye of Jupiter that turned out to be significant in Season 3 of Battlestar Galactica (Reimagined) 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...
- Ultra Series: The Magnerium Medicalizer was used by the Terrestrial Defense Force's Ultra Garrison to revive a crucified Ultra Seven, and was not used again until over 30 years later to save Ultraman Mebius!
- 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 finally.
- 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.
- 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.
- 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.
- Older Than Feudalism: An example from Greek Mythology, starting with the Archaic Catalog of Women. A boomerang on several levels: when Heracles (better known by his Roman name, Hercules) slayed the Hydra, he dipped his arrows in its poisonous blood thinking that 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.
- Discworld II: Everything from the pot of glue through the art of beekeeping to the continual theft of stuff from Mrs. Cake's house.
- The Secret of Monkey Island: The root beer.
- The Cane of Pacci in The Legend of Zelda: The Minish Cap. 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.
- Not all that uncommon in the other Zelda games, as the player's inventory can become rather stuffed.
- One of the more prominent examples is in 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.
- In 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.
- 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.
- Numerous pieces of evidence in the Phoenix Wright: Ace Attorney games show up in multiple contexts in the same case, or even pop up in multiple cases as Continuity Nods. One example is 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.
- In the first case of Phoenix Wright: Trials and Tribulations, a major piece of evidence is Dahlia Hawthorne's bottle necklace, which contains poison. When she shows up in the fourth case, the poison in the necklace is used again by Terry Fawles.
- Not to mention the fact that a person's appearance changes during a channeling.
- Anyone count how many times Trucy's Panties is used to object to testimony in the second case of Apollo Justice? Many lost count well before the judge commented on Apollo's repeated presentation of that piece of evidence.
- 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 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 Neoquest II, an RPG in Neo Pets, the sword you start off with is also the best sword to use against the final boss.
- Paula's Pray ability in EarthBound 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.
- 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.
- 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.
- 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.
- 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 Chekov's Yo-Yo. You use it, then again, then again, then again, then again...
- 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."
- In Halo, 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 and prevents the destruction of half the galaxy. In the end of Halo 3 the Flood has taken control of 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 ones are destroyed. With an almost completed ring inside the station, everything needed would be an Index to activate it. "I'm a thief... but I keep what I steal."
- 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.
- 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.
- 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.
- 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.
- An example of good game design theory. The earlier uses of the incinerator and rocket launcher teach the player, setting up for their combined use in the boss fight.
- In fact, the commentaries for many of the Half-Life games mention this style of game design. Show the player something, let them do that something, and then let them do that something while in a dangerous situation. Generally there isn't as much lag between the intial teaching and the usage of that skill, but it sorta counts.
- The sequel has another example: near the beginning, you trick the system responsible for throwing out defective turrets into throwing out working ones and keeping the defective ones. Soon afterwards, GLaDOS throws turrets at you - which are defective. Near the end of the game, Wheatley sets up an obvious death trap... full of defective turrets.
- Portal 2 is a game where nostalgia fights to create an unrelenting march of Chekhov's Boomerangs, all while introducing new ones.
- 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.
- In 7 Days a Skeptic you use the wrenches more than once.
- And in the previous game, you were forced to use the "Salty bear on a stick" trick more than once. No, seriously.
- 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 when Shiro traces the Rule Breaker and uses it to break Sakura's connection with Angra Mainyu
- 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.
- The birdseed in the third episode of Wallace & Gromit's Grand Adventures is used for 3 separate puzzles.
- 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.
- God of War has Pandora's box
- In Wild ARMs Cecelia's Tear Drop item comes back several times.
- 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.
- 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.
- Broken Sword: Shadow of the Templars has the manhole-opening tool.
- 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.
- In Metal Gear Solid 3, Big Boss 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 Big Boss 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.
- 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.
- 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.
- 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 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.
- 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).
- 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.
- In The Order of the Stick, Belkar aquires 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.
- Sinfest: Glitter points really come in handy a lot.
- 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.
- 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.
- In the very first Global Guardians story, Dogfight's status as a husband and father is remarked on by his teammates, as it is relatively rare for costumed crimefighters to be married, much less to be married with children. Years later, when Dogfight is killed rescuing people from the World Trade Center during the September 11th attacks, his family is brought front and center to add a bit more poignancy to the memorial for the attack's victims. They then disappeared into the background, presumably never to be seen again. In one of the last Guardians stories, Dogfight's oldest son reappears as a supervillain (having inherited his father's powers) seeking revenge on the Guardians, whom he blames for his father's death.
- In Noob Sparadrap's cheated staff is one. He got it in Season 1, the fact it's overpowered and a present from Tenshirock in 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.
- 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.
- A lot of the stories in Donald Duck & Co. works with a Chekhov's Boomerang returning in the end and solving the plot.
- 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!
- Torgo's Executive Powder from Futurama. It's got a million and one uses.
- 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.
- 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.
- 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.
- 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.
- In an episode of Dexter's Lab where Dexter has to combat an alien life form that's possessed all his family members, he use's 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".
- 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..
- Timmy Turner uses his magical time-traveling scooter several times during the series. He also somethings uses other magical items more than once
- 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".
- 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.
- The Talismans in Jackie Chan Adventures pop up several times after the first season.