Neo: Its a city?
Tank: The last human city.
Neo: Where is it?
Tank: Deep underground near the Earths core, where its warm. You live long enough, you might see it.
A plot element that doesnt get fully developed, perhaps on the assumption that theyll have the sequel to take care of it. The element can be a relationship, a theme, or a character that clearly has a lot more possible development, but doesnt get it. The central plot is no less complete and these aspects may have just been there to enlarge the universe, but they're there and available for later use — more story to tell later. This can backfire if the sequel doesn't get made.
Compare Sequel Hook, which only occurs at the end of the story and is specifically geared toward inviting a sequel, Development Gag, where hints of certain pathways the story could have taken are left as tidbits, and Refitted for Sequel, where an element is dropped from the original production only to be modified to fit a later work.
The mouse in What Happened to the Mouse? can seem like one of these, but unlike a mouse, something that has been saved didn't disappear, it just wasn't resolved— it is still present.
When this happens excessively, this will develop into a Kudzu Plot.
- Arachnid gets an ending with little closure for the heroine and several loose ends, but years later the sidestory Caterpillar became a P.O.V. Sequel after its prequel arc.
- Reinforce Zwei of the Lyrical Nanoha series. During A's she was the very definition of Last Episode, New Character; she only had a single line at the very end of the last episode of the season. Come StrikerS onward however she gets considerably more characterization and screen time.
- Nagisa Momoe, the Magical Girl form of the witch Charlotte/Bebe is introduced in Puella Magi Madoka Magica the Movie: Rebellion. Despite the hype for her appearance and her prominent placement in advertisements for the movie she gets very little characterisation or build-up compared to the other magical girls. Word of God says that if they ever do make a sequel to Rebellion they intend to do a lot more with her character.
- Despite originally being touted as the "secret origin of Spider-Man", The Amazing Spider-Man left a lot of unanswered questions about Peter's parents and the nature of their experiments, which were finally addressed in The Amazing Spider Man 2.
- Likewise, The Amazing Spider Man 2 doesn't really resolve the situation with Harry's condition, and only introduces the Rhino for a Sequel Hook concerning the Sinister Six.
- Marvel Cinematic Universe:
- A deleted subplot from The Avengers focusing on Captain America's attempts at rebuilding his old life (which ended up only alluded to) was included in Captain America: The Winter Soldier.
- In Iron Man, Rhodey looks at the silver prototype Iron Man suit and says, "Next time, baby." Unintentionally funny in that Rhodey had been recast by the next film where he actually gets to wear the armor.
- Early drafts of the script for Captain America: The First Avenger had Baron von Strucker as a side villain working under the Red Skull, the film's Big Bad. The writers felt that using Strucker in such a minor role would be a "waste," so they wrote him out. He eventually made his debut in The Stinger of Captain America: The Winter Soldier, and was used briefly as one of the villains in Avengers: Age of Ultron.
- According to Joss Whedon, an amazingly awesome, fist-pumping Hulk moment from the climax of Age of Ultron was cut for disrupting the flow of the finale. He cited this trope as his reason for not revealing what it was, since Marvel can use it in a future film.
- Batman Begins is an excellent example. When it ended, the plot was resolved, but there was unresolved romance between Bruce Wayne and Rachel Dawes to provide fodder for the next movie.
- This is attempted with Humma Kavula in The Hitchhiker's Guide to the Galaxy movie. The Point of View Gun was clearly setting up a plot where he tries to brainwash everyone in the galaxy and take Zaphod's place. Too bad there won't be a second movie to make these things worthwhile.
- The Phantom Menace and Attack of the Clones ended with several plot points dangling to be picked up in the next installment. Technically, even the last movie of the prequel trilogy, Revenge of the Sith, ended with dangling plotlines... which were already resolved in the original Star Wars trilogy.
- In The Force Awakens the fate or identity of Rey's family is never revealed, but it has been confirmed that that issue will be resolved later on in the sequel trilogy. As of The Last Jedi, they have been revealed by Kylo Ren to be nobody important - drunkards who sold their daughter for drinking money and abandoned her on Jakku. Whether this is true or not is yet to be seen.
- In TRON: Legacy the son of the bad guy from the original TRON, played by Cilian Murphy, appears as an Encom board member, but does little save prove his technical savvy and quick mind. With his connection to the history of Tron and the plans for a third movie, it seems likely that he was there to foreshadow a larger role in that plot.
- According to Word of God, in Godzilla (1998) there were going to be other kaiju, but they got held back to appear in the sequel. Perhaps if they had put them in the movie there would actually have been a sequel.
- In the first Christopher Reeve Superman film, General Zod is roaring to Jor-El, "You will bow down before me, Jor-El! Both you and, one day, your heirs!" However, he is then cast into the Phantom Zone and we have to wait to the next film to see him carry out that threat.
- Green Lantern has Sinestro, traditionally Hal Jordan's nemesis as a fellow member of the corp. While this fits in with comics continuity, one gets the feeling that this wouldn't be the case if Warner Brothers wasn't hoping to make it into a franchise.
- G.I. Joe: The Rise of Cobra is, of course, the story of the rise of Cobra. So Cobra Commander doesn't become Cobra Commander until the last couple of scenes, setting up the sequel G.I. Joe: Retaliation.
- Borderline example in The Hobbit, which includes some of the retcons and context that in the original books were included in the sequel The Lord of the Rings. It sort of fits in this trope because unlike the books, The Lord of the Rings movies were made first, and The Hobbit movies are effectively a prequel.
- Averted in the first Terminator. There were a couple scenes filmed in which Sarah discovered SkyNet's origins in Cyberdine and suggested to Reese that maybe they should try to destroy it to prevent the future war as well as a longer ending in which it was revealed that Cyberdine picked up the destroyed Terminator chip and arm, both setting up events that would occur in Terminator 2: Judgment Day. James Cameron ultimately had these scenes cut. (Though the sequel still used these ideas)
- The Golden Compass omitted the scenes at the end of the novel on which it is based, in which Lyra inadvertently betrays her best friend to her father and costs the boy his life. We should theoretically have seen those at the start of The Subtle Knife. Then the whole thing fell through.
- Although the Mutos of Godzilla (2014) were introduced as Canon Foreigners rather than updated versions of classic Toho monsters in order to give the film a bit more narrative freedom, Gareth Edwards has jokingly stated that he is contacting the casting agents of creatures like Mothra and King Ghidorah so that they can appear in sequels.
- The character of Gambit has been hit by this several times. He was originally intended to make a cameo in X2: X-Men United, (he ended up just being a name on a computer screen) but it was decided to save the character for X-Men: The Last Stand. After being written out of that film as well, he finally appeared in X-Men Origins: Wolverine. After that film was declared Canon Discontinuity, there were plans to re-introduce Gambit in X-Men: Days of Future Past, which also failed to materialize. He's currently set to appear in X-Men: Apocalypse, played by Channing Tatum.
- Jubilee got hit with the same thing. She was originally supposed to appear in Days of Future Past as one of the future X-Men, but was cut for unknown reasons. She'll instead be used in Apocalypse as one of the new recruits.
- The Stinger of Deadpool has Wade telling the audience that Cable is planned for the sequel.
- Early drafts of the script of Spider-Man had both the Green Goblin and Doctor Octopus as villains. Seeing as how they didn't want to overcrowd the movie with three different origin stories, Doc Ock was cut from the film and later showed up in Spider-Man 2
- Early drafts of Teenage Mutant Ninja Turtles (2014) featured Casey Jones, Beebop and Rocksteady, but all three characters ended up being written out. They'll be appearing in the sequel.
- In the first Anonymous Rex book, Vincent's partner has been killed, leaving him a cynic, but how it happened is left unsaid. The second book is a Prequel where at the very end the death happens.
- Brandon Sanderson says that he has many developments in BioChroma that he plans to put into a sequel to Warbreaker named Nightblood. However, he is not entirely clear on if he will actually write it, and it has been put on hold until after he establishes his The Stormlight Archive series in the same Verse.
- The $30 expansion for Saints Row: The Third titled Enter the Dominatrix (originally thought to be an April Fools joke, but later revealed to be real) was announced to be canceled but later released for the next game.
- During the final mission of Star Fox: Assault, the Star Wolf team (who are allies to the Star Fox team for the moment) draw off the enemy ships pursuing the Star Fox team, allowing them to reach the game's Final Boss, and are not seen again, leaving it unclear whether they survived. There has been another game released in the series since then and all three members of Star Wolf did appear, confirming that they did survive, though there is ongoing debate among the fandom over whether that game is canon or not.
- BlazBlue: Calamity Trigger does not explain what exactly happened to Arakune, why Litchi is so bent on rescuing him, what Hazama is up to, who he works for, why Carl is looking for his father, what "Amaterasu" is, who the other five of the Six Heroes are, among many other plot details, creating a Mind Screw in general. BlazBlue: Continuum Shift, the sequel, answers these questions and brings up more. For instance, now that we know Carl is looking for his father because he's an absolute scumbag, we learn that he is a Chessmaster villain but nothing about what he wants or what he intends to do. Arakune is regaining sentience, but Litchi is about to do to herself what Arakune did before. Bang has the power to close portals to The Edge but has yet to have an opportunity to use it. And so forth.
- Mass Effect 2:
- The Quarians are worried over a remote star dying far faster than it ought to be. Tali hypothesizes it's due to dark energy affecting the interior of the star, but remarks that no race has the ability or any particular motive to destroy one. Nevertheless, she voices concern over the possibility of an adversary powerful enough to take a star out. The explanation is left open for Mass Effect 3. Amusingly, this has ended up as an Aborted Arc - it's one of the few dangling threads that isn't addressed at all (not even in one of Shepard's emails). Perhaps it will be addressed in the expected new storyline set in the universe.
- Originally this was supposed to be the motive for the Reapers. They were intended to be interested in stopping the spreading of Dark Energy before it could tear the universe apart. And the key to this was biotics. This was replaced with the ending of the entirety of the story being about the Reapers as a Rouge A.I. Given the level of reception of the ending, it seems that this could have been better, though that is likely just because the current ending is so unpopular.
- Pokémon Black and White left a number of loose ends that weren't wrapped up when the story was finished. Fans were expecting a "Grey Version" following the pattern from past generations, but instead full sequels were released: Pokémon Black 2 and White 2.
- While Pokémon X and Y did have Zygarde as a Bonus Boss, the anime featured formes for it not found in those games. Because there was no Updated Re-release or sequel for the Kalos games note , those extra forms were put into Pokémon Sun and Moon (and its Updated Re-releases, Ultra Sun and Ultra Moon) as a sidequest.
- Leaf, the female protagonist of Firered and Leafgreen, is a redesign of an apparently unused female protagonist from Pokémon Red and Blue. This design was used as the basis for Green in Pokémon Let's Go, Pikachu! and Let's Go, Eevee!.
- Tirtouga greatly resembles an unused Pokemon from gen 2.
- On the subject of Generation 2, Pokémon Gold and Silver were originally going to contain a skateboard in addition to the bicycle; an idea that ultimately never made it into the final game. Years later in Pokémon X and Y, the player character is given roller skates in addition to getting the bike later on.
- Originally, Professor Oak was going to be the final battle before becoming the Champion in Pokémon Red and Blue. Twenty years later, in Pokémon Sun and Moon, the final battle is against the Alola region's own Professor, Kukui.
- A grass-type Eeveelution was planned for Gold and Silver. Nearly ten years later, Diamond and Pearl introduced Leafeon.
- The PlayStation version of Soul Edge, known outside of Japan as Soul Blade, was intended to feature certain characters as guest characters but in the end there wasn't time to implement them. Among these guest characters would have been Arthur, Kathandra and Monkasei. Arthur would appear in Soulcalibur as an optional replacement for Mitsurugi in Arcade machines (mainly for the Korean market but available in American ones too). Kathandra would be renamed to Cassandra and first appear in Soulcalibur II. Monkasei would be reworked into Yunsung and also first appear in Soulcalibr II (with his name instead being spelled as Yun-seong from III onward).
- Super Smash Bros.:
- Bowser, King Dedede, and Mewtwo were meant to be in the first Super Smash Bros. on the Nintendo 64; they did not get in due to time and budget constraints. Bowser and Mewtwo would eventually make it into Melee, while King Dedede would not join until Brawl. Pit was also considered for Melee as a retro character (among many other characters), but the Ice Climbers were added over him due to their gameplay potential. Pit would go on to join in Brawl, with an updated appearance, which would lead to a new game after over two decades.
- Miis were also considered to be added in Brawl, but Sakurai decided against adding them, because, at the time, he could not figure out how to implement them. They join in the 3DS and Wii U iterations as fully customizable characters.
- The Villager was considered to join the battle in Brawl, but Sakurai likewise decided not to include him because Animal Crossing being about as peaceful as a video game series can get, he couldn't think of any good moves to give him. By the time the fourth game started development, he eventually did find good moves for him, and thus the Villager became playable.
- Shigeru Miyamoto personally requested Pac-Man be made a playable character for Brawl (Pac-Man is his favorite video game character), but Masahiro Sakurai was unable to think of a good moveset at the time. He would make his debut in U/3DS, and indeed, most of his attacks there draw inspiration from other Namco games rather than his home series alone.
- Final Smashes were intended to be included in the original Nintendo 64 game, as evidenced by unused audio files, but weren't added in until Super Smash Bros. Brawl on the Wii.
- Sonic the Hedgehog:
- Due to Sonic 3 & Knuckles being split in two parts because of time constraints, most plotlines, the second half of the story, and most (if not all) of the Sonic & Knuckles content ended up becoming this.
- Flying Battery was originally going to be a Sonic 3 stage placed between Carnival Night and IceCap, but they choose to save it for Sonic & Knuckles, feeling that this one would be too short otherwise.
- Hidden Palace was going to be a hidden Sonic 2 stage where Sonic would gain his Super form after collecting all Chaos Emeralds, but had to be scrapped due to time constraints. Two years later, the stage was incorporated into Sonic 3 & Knuckles, albeit using different layout, graphics and music, but keeping its concept, function (replacing Super Sonic with Hyper Sonic) and lore (albeit altered to fit with the game and the established canon), even making the area more of a central element in the story. Eventually, the 2013 smartphone Sonic 2 port added back the Zone as an extra bonus, but it stripped it off its functions and lore and changed it into more of a prehistoric-themed stage to differentiate it from the S3&K incarnation.
- A more minor Sonic example was the Sunset Park Act 3 theme from Sonic the Hedgehog: Triple Trouble. It was originally supposed to be used in Sonic the Hedgehog Chaos, but was Dummied Out before finally being used in Triple Trouble... to the delight of many fans, who consider it to be the best song in any 8-bit Sonic game.
- Time-traveling was a concept first conceived for Sonic the Hedgehog 2 but wasn't added into a game until Sonic CD. The unused Rock World Zone was the 'past version' of the more well-known, also unused, Dust Hill Zone.
- Vector was originally supposed to be part of a rock band with Sonic in the first game. The concept was scrapped when they couldn't implement the characters in the game, as a sound test mode intended to show them had to be cut out due to memory limitations. He was reintroduced in Knuckles Chaotix.
- Due to Sonic 3 & Knuckles being split in two parts because of time constraints, most plotlines, the second half of the story, and most (if not all) of the Sonic & Knuckles content ended up becoming this.
- Nova Terra was the main character of the StarCraft Gaiden Game Starcraft: Ghost, a third-person shooter. The game went through a long Development Hell until it was finally cancelled, but Nova becomes an important side character in StarCraft II.
- Some elements of Warcraft II's backstory (especially concerning the different human factions) weren't seen in Warcraft III, but returned with a vengeance in World of Warcraft.
- The Legend of Zelda:
- The Horse Call in Twilight Princess dates back to Ocarina of Time. It was originally a Reed Whistle but was scrapped in favor of Epona's Song.
- The Hero's Shade teaching you moves in Twilight Princess is similar to an unused concept for Majora's Mask where Link learned skills via cutscene.
- The Legend of Zelda: The Wind Waker uses various unused concepts from The Legend of Zelda: Ocarina of Time. It's speculated that Fado the wind sage is a reference to Fado from OOT, who seems to have had been a sage in development instead of Saria. There are also some Dummied Out temples and other elements from earlier stages of Ocarina Of Time that were retooled in Wind Waker.
- The E3 announcement trailer for The Legend of Zelda: The Wind Waker shows that Link originally had a sneaking ability for stealth portions of the game. It was replaced with hiding inside barrels. Years later The Legend of Zelda: Breath of the Wild implemented a stealth ability.
- Crash Bandicoot: Tiny Tiger and the Komodo Brothers were supposed to appear in the first game, however they were held back until the second title.
- In Noob, Omega Zell and Gaea were meant to both have something big happen to them at the end of Season 5, which was supposed to be the last of the webseries. Part of Season 5's production ran concurrently with a crowfunding campaign meant to finance a movie that would be a sequel to the webseries. When the crowdfunding turned extremely successful, the creator decided to move these big moments to Noob: Le Conseil des Trois Factions so they could be made more impressive than if they had happened during the webseries.
- Avatar: The Last Airbender was initially supposed to go in-depth about the origin of the Avatar Cycle. This was cut for time and instead covered in season two of The Legend of Korra.
- Korra itself has this to a smaller extent in the form of Kuvira, who appeared briefly in the finale of Season 3 (with a very noticeable character model and soundtrack, mind you) before returning with a much larger role in Season 4.
- The Simpsons episode "I'm Spelling as Fast as I Can" was going to have a Lead In where Bart realises he wasted his summer and rushes all the activities he intended to do on the last day. It ended up being cut for time and used in "The Monkey Suit" instead, three seasons later.
- The Steven Universe episode "Hit the Diamond" was going to have a scene where Steven gives nicknames to the Ruby Squad, but it ended up being cut. It took until "Back to the Moon", the Squad's second appearance, for the nickname scene to happen.