The Trope Namer was one very brief scene in 1987's The Last Emperor, when a character flings his pet mouse out of shot while standing in a hallway. The mouse is never mentioned again, leading some audience members to invoke the trope by name. The Extended Cut released on DVD answers the question. The answer: About what you'd expect when a mouse is thrown against a wall, although the mouse used for the shot was not real and no mice were injured in making the film.
After the razing of the village by the slavers, the children were simply left behind by Middle Eye and the rest of the hunters. None of them are seen again in the end, leaving many Unfortunate Implications and Fridge Horror behind. It's possible that they simply fled deeper into the jungle to make new homes, just as Jaguar Paw and his family did at the end of the film.
Blunted's mother-in-law also disappears from the story. When the slavers reach the city and put their slaves on the auction block, the mother-in-law is dismissed as a "useless old woman," and when the slavers realize they won't be able to profit from her, they simply set her free. The old lady just wanders off and disappears into the crowds on the streets. You never learn what became of her, so it can only be assumed that she stayed in the city until she died.
In the first film you never know what happened to the stolen embryos: They are last seen being rapidly buried in the mud; the subplot involving InGen's rival company BioSyn and its attempt to seize the dinosaur embryos as well as its sleazy representative, Lewis Dodgson, also disappear in the sequels (although they were the major antagonists in the sequel novel, they were left out of the movie adaptation). Since the embryos only had a few hours of coolant, it's presumed that they rotted.
The tie-in video game reveals the fate of the embyros. They were destroyed by a Tyrannosaurus.
You also never learn the fate of the sick triceratops from the first film. The bookexplained that the stegosaurus had gotten sick from eating poisonous plants when picking up gizzard stones. This was dropped from the film (possibly due to time constraints). Instead you hear that it was NOT the poisonous plants which leaves the poor triceratops' fate unknown.
The Wild Women of Wongo. For the first half of the movie it's established that a tribe of "Ape Men" are about to attack. A grand total of two show up, get killed, and the whole invasion is never mentioned again. So two men are a tribe, then?
The main character's bad friend drags him down the wrong path for the first half of the film, but around the halfway mark, after a scene where the friend literally kicks a dog, both the friend and the dog disappear from the story. Neither are ever mentioned nor seen again.
The movie never says what happens to Paul either.
In Iron Man 2: The fate of both of Ivan's birds is left unstated.
The Room. Most of the plotlines are left unresolved. Some are discarded the moment they are introduced. What happened with the drugs, or the breast cancer, or the new client at Johnny's bank, or Mark thinking about moving to a new place, or Peter the psychiatrist?
Spice World lampshades and subverts this when Melanie C asks the viewers: 'what happened with the bomb on the bus?'
In the TV movie adaptation of The Christmas Shoes, the main character's mother dies. As The Nostalgia Chick points out, no one ever brings it up again for the rest of the movie.
The Wicked Witch of the West mentions as she sends out the flying monkeys that she is "sending a little insect to take the fight out of them." This was a reference to the Cut Song "The Jitterbug", which would have followed that scene, which was cut because the producers feared the number (which was a very 30s style high-energy song) would date the movie.
Toto's fate is left unresolved, though the filmmaker's intended the death of the Wicked Witch of the West is supposed to be a parallel for Miss Gulch being killed by the tornado. The illustration at the beginning of her on her bike flying through the air was supposed to be real, although her turning into the witch was just Dorothy's imagination.
The first time, it's not too bad — Drew is knocked unconscious and wakes to the sound of a blender. If you can hear over the bad sound-mixing, Creedence has announced that she's going to feed him a milkshake full of that slime that turns you into a plant, and implicitly, full of Arnold as well. So it can be assumed that Drew gets eaten.
However, Brent's disappearance from the film is nothing short of baffling: after the infamous popcorn sex-scene, you get a brief shot of him covered in popcorn muttering "no more, no more popcorn", and then he's gone from the rest of the movie. He's not even in the car when the Waits family and Elliot drive back from Nilbog.
In It Came from Outer Space 2 a blob engulfs various terrestrial life forms, starting with a coyote, and sends alien copies of each one out into the world. At the end, the blob turns back into a spaceship and flies off, leaving all the humans it engulfed behind... but what happened to the coyote?
Cult film The Doom Generation has a disproportionate number of these. Multiple characters vow revenge on the protagonists after mistaking one of them for a former lover, but only two of them ever show up again. The FBI is shown holding a briefing about the protagonists' involvement in a murder-suicide, but they never show up again. It's a weird movie.
In Mystery Men, Dr. Annabel Leek, the Big Bad's lover and henchwoman, simply vanishes without a trace halfway through the film and is never mentioned again. In the comic book adaptation, she gets killed by Casanova Frankenstein. When he started paying too much attention to the kidnapped Monica, she ordered him to get rid of her. She thought that he was her obedient puppet. She was wrong.
Apocalypse Now: What happened to the dog? This is still the most asked question by all the actors from the film. There is also the matter of the surfboard. Apocalypse Now Redux includes a lot of deleted scenes which answer most of the questions (but still leaves a few hanging).
The Movie of Mystery Science Theater 3000 had an infamous one where Crow picks up a chainsaw in Tom's room and even says "Hey, a chainsaw!" Nothing else happens with this afterward, thanks to Executive Meddling forcing a completely different ending than the original one where Crow uses the chainsaw in yet another escape attempt. It still more or less works as a random throwaway joke.
In Cannibal The Musical, Alferd Packer spends much of his time in prison building a dollhouse, which never amounts to anything. Trey Parker says this wasn't really supposed to be a plot point, and was just a reference to the real Alferd Packer's hobby of building dollhouses, but he admits there should have at least been a scene where he finishes the dollhouse.
About 20 minutes before My Fair Lady ends Col. Pickering decides to search for poor little Eliza who went AWOL. He determinedly walks out of the library set - and is never seen or heard from again.
Quentin Tarantino's Death Proof: What happened to their actress friend Lee, whom they left alone with a creepy hillbilly Jasper? It seems unlikely that Jasper would try anything too criminal, given that he knows several people will be arriving to collect her in a few minutes. However, Word of God says that Jasper, who also appears in Kill Bill, does in fact rape her.
There is a goose that turns up for the first half hour. It is never explained why the family has a goose or why they can't sell it. After its few scenes it is never seen or heard from again. Made more frustrating due to the goose having no impact on the plot and is simply introduced only to disappear.
In the stage show it's simply comic relief—doesn't impact the plot in any significant way, but as the second act of the show (and the latter half of the film) is soul-crushingly sad, you see where they're coming from with the lighthearted moments.
In the short "Cookoo Cavaliers", the Stooges run a beauty salon. When asked to bleach some women's hair, they inadvertently take out some bottles of hair remover. At one point, the hair remover gets sprayed all over a dog, and Curly is shown beginning to wipe off the dog with a towel. But the dog is never seen again, despite this being a very obvious setup for a joke where the dog's fur falls off.
The short "Oily to Bed, Oily to Rise" has the Stooges destroy the saws of a farmer. The farmer warns them that they will work for him until they pay for the broken saws. However, in the next scene, the Stooges are walking on a dirt road. We're Left Hanging as to what happened with the farmer - did the Stooges replace the saws or did they run out on him when he wasn't looking?
What happens to the third Treadstone agent, Manheim, in The Bourne Identity? He shows up throughout the movie, does his job and vanishes. Then in the next movie, Bourne meets a guy named Jarda who says they are the last two agents. Did Manheim get replaced?
In Arachnophobia, Ross' friend Chris survives the spider infestation and manages to escape from the house with the family; he is last seen trying to pull Ross out of the house on a ladder but is knocked over. He is never seen again after that.
In the original version, considerable emphasis is placed on the old man's puppy for much of the film. It precipitates several important scenes, and is shown to be okay after each Blob encounter. Until the supermarket scene (which it clearly survived). After that, it is never seen or mentioned. Even Jane's little brother, who was promised the puppy and was very excited about it, never brings it up.
The old man's dog in the remake isn't accounted for either, but it's only in two scenes, so it isn't nearly as odd.
When Steve and Jane go to the movie theater to enlist the help of Steve's friends to warn the town of the blob, the girlfriends of Steve's friends also go along to help. Once they get the attention of many of the townsfolk, Steve's friends stick around, but their girlfriends disappear for the rest of the movie.
In House of Flying Daggers, the eponymous society has been discovered and the police have been sent in. There's a shot of a few troops advancing cautiously through the bamboo forest. Then, the fate of the House and the police are dropped in favour of the main characters dying very slowly. This is due to Anita Mui dying before she could film any scenes as the Flying Daggers' leader. Director Zhang Yimou felt that hiring another actress would be disrespectful, so instead the film's second half was heavily reworked.
There's a particularly monstrous moment of this in the dire Duel knock-off Wheels of Terror: the heroine is driving a bus full of schoolchildren when she decides to chase the car that's just abducted her daughter. She lets the schoolchildren out at an abandoned gas station in the middle of nowhere, and they are never mentioned again. There's an explosion, which may have been meant to indicate that they died, but it's not very clear.
In The Rats, the heroine's friend Jay is the first person to be bitten by the rats. She survives the attack but is then hospitalized with septicemia and halfway through the movie a scene establishes her as being in a very critical condition. It's never revealed whether she lives or dies and she is never seen or mentioned again after that scene.
In Poltergeist III, teenage couple Donna and Scott are pulled through a Portal Pool and onto the Other Side. Then, at the end of the film, Donna is returned safe and sound to her family. As for Scott? The film crew reluctantly admitted that, when they did a last-minute reshoot of the ending, they simply forgot about him. The question of what happened to Scott took on new life as the internet brought fans together to offer their own theories: presumably, he's still Trapped in Another World.
In Metropolis, Freder agrees to stand in for an exhausted worker, telling him to go to his servant Josophat's house for the time being. The worker instead steals Freder's money and goes on a spree through the city's pleasure district. A subplot involving him originally followed, but due to missing footage (some of which was only recently discovered), nearly all cuts of the film currently available omit any further mention of him. More deleted footage was found in Argentina in 2010, including scenes that show what happened to the worker after stealing Freder's money.
Pans Labyrinth: When Ofelia escapes from the Pale Man, she breaks her chalk and leaves a piece behind, and this action is filmed in such a way as to make sure the viewer knows that there is a piece of chalk there that the Pale Man could use to escape. Straight into her bedroom, no less. And while that would have undermined the ambiguity of the film, that same ambiguity made it worryingly possible.
Several early scenes in Crocodile Dundee imply that Mick is a croc poacher, but this is never mentioned again once they get to New York. It might simply be intended to convey that Mick is an irreverant rural type who plays by his own rules rather than follow the laws of civilized society, which is basically how he stays.
Sophie. When she and the other two Piper kids left for school, she completely vanished from the movie. You think she would've cared about the main plot where if Marnie fails to make the Halloweentown High student transfer a success, then her family's powers could be taken away. It's pretty blatant that the creators didn't care for Sophie anymore now that she aged.
This is evident in Return To Halloweentown where Sophie and Grandma Aggie got Put on a Bus. Even then, Grandma Aggie at least had two appearances; Sophie was only briefly mentioned.
Luke never gets any appearances or references past the second film too.
Kal gets no mention in the second film, even though he is said to not have been destroyed. Yet he never shows up again.
In Hallmark's 1999 adaptation of Alice in Wonderland, Alice saves three playing cards who were about to be beheaded by the Queen of Hearts for planting white roses instead of red ones, by telling them to jump into her pocket. That's the last anyone ever hears from them. In the book she hides them in a flowerpot, leaving them to get out later by themselves once the heat had died down.
The Coca-Cola Kid actually introduces a real mouse early on in the story, and shows the main character interacting with it briefly a couple of times, although it seems to be destined to be forgotten since it has no significance in the plot. But, in a wonderful case of last-minute trope aversion, the mouse plays a notable role in the final scene.
In Halls of Anger, some white teenagers are bused to a predominately black school. The blonde girl gets cornered in the locker room by some black girls who proceed to rip her clothes off. Cut to a race riot outside, the standard Teacher Who Wants to Make a Difference (is this a trope?) makes a rousing speech to calm everyone down, The End. What happened to the blonde?
In Big House, USA a man named Baker is arrested for kidnapping a boy named Danny and holding him for ransom. Danny was not in the fire tower where Baker left him. Even the narrator at the end of the movie admits no one knows what happened to Danny.
There are 10 "Basterds" in Inglourious Basterds, not counting Hicox, but counting Aldo Raine, Hugo Stiglitz, and the "eight. Jewish. American. soldiers." Two are onscreen, alive, in the final shot, two die in the theater, two more die in the tavern. That leaves four Basterds whose fates are unaccounted for. The script says that everyone else is dead by that point.
In The Mummy Returns, Imhotep resurrects four palace guards. All four charge out of the museum and crush Rick's car. However, only three of them are accounted for in the ensuing fight scene. According to the original script, the fourth was supposed to attack Alex after the bus had come to a stop. However, director Stephen Sommers decided to cut the scene short in order to get on with the story.
Mr. Bigglesworth, Dr. Evil's bald cat in the Austin Powers films, is only seen in a flashback (with full hair) in the third movie. What happened to him in present day? Presumably Mini-Me took his place as Dr Evil's (and the writers') pet.
In the 2009 movie Obsessed, Lisa the stalker apparently gets flowers complete with handwritten card from the man she's after, Derek (who wants absolutely nothing to do with the woman), while she's in the hospital. The movie never explains how she got them or who wrote the card, and they are never mentioned again in the film.
In The Day After Tomorrow Sam Hall's rival for Laura's affections talks about trying to get to his younger brother early in the film. The last mention of this is just before Sam almost drowns while calling his dad. It's implied that the brother dies in the tragedy.
Shaun of the Dead has several that are addressed in DVD extras, such as how Shaun lured the zombies away from the pub and survived, how Shaun got zombie Ed back to his house and what happened to Diane who just disappeared into a crowd of zombies at one point near the end and never seen again (she managed to climb into a tree where she passed out, woke up when all the zombies were gone and order was restored, but decided to stay up in the tree anyways just to be safe where she survived by eating her boyfriend's leg).
Ginger Snaps has one of these. While the core of the plot revolves around the two sisters, their mother, and the older sister's boyfriend, the girls' father is an important secondary character. He is last seen briefly just before the climax of the film begins, and is never seen or heard from again.
The Grim Reaper is apparently still running amok in the "real" world at the end of Last Action Hero. Since he declares that he's following a list, and doesn't touch people who aren't on it, he presumably doesn't make any real impact on the world - he only touches people who would have died anyway.
In Friday the 13th Part 2 there is a major character who is last seen at a bar and apparently gets forgotten about entirely by the film. Fans all wanted to know what happened to him. The actor who played him said in an interview that he had always thought the man probably hooked up with a waitress and had a one-night stand.
In Friday the 13th: The Final Chapter (aka Part IV), Gordon, the dog, is last seen jumping through a window to escape Jason. He's never seen him again following this. Likewise, Trish does not appear in the fifth or sixth films, even though she survives at the end.
In the first act of A Bronx Tale, the main character Calogero is 9, living with his mother and father. There's a Time Skip for the second half of the movie, which takes place about 7 or 8 years later, and his mother is never seen or mentioned. This is a shame because logically she might have been very useful in patching up the strained relationship between Calogero and his father Lorenzo.
In the movie of The Addams Family, Tully and Margaret Alford's son, who appears in one scene (and in the credits as "Tully Jr.") but despite the fact that his mother runs off with Cousin Itt and that his father is buried, possibly alive, in the Addams' graveyard, he's never spoken of again, not even in Addams Family Values. The most likely resolution is that he was taken in by relatives of his father.
The fate of Nauls. During the final confrontation, he walks off down a corridor in the Arctic base and vanishes promptly from the film. The original script had him getting attacked by a jack-in-the-box like alien, only they cut the scene as the special effects didn't look real enough, and Carpenter liked leaving it ambiguous anyway. It's almost certain that he just got killed off-screen, but it's never actually resolved.
In The Stupids, the main antagonist, the colonel, is last seen when Harvey Atkin's character hits him with a door, knocking him out. You never know what becomes of him later.
In the Steve Martin movie, LA Story, several characters are very impressed with the reputation of agent Harry Zell. Many different conversations mention him, and Steve Martin himself complains about his current agent, saying he wouldn't get such bad gigs if he worked with Harry Zell. After such a build-up, Harry Zell never appears. Deleted scenes show that Harry Zell is played by an over-the-top John Lithgow, who flies around with a rocket pack, and encourages Steve Martin to skip from place-to-place. (It's the new walking.)
In Splash, Freddie is last seen distracting the cops after helping his brother rescue his mermaid girlfriend. The head scientist orders him arrested, and that's the last time he's seen. Kind of a dark character ending for such a frothy movie.
In the movie Daddy's Girl, near the middle Jody murders her mom's friend Rachel and her death goes unmentioned for the rest of the movie.
Puppet Master I had an oriental puppet in the beginning that was placed in the box by Andre Toulon along with the other puppets, hidden away safely. He was never seen again. This also goes to the maid of the Gallaghers. Despite being revived and guarding an exit, she suddenly just disappears out of shot and is never noted again.
The Harry Potter films are a bit tricky regarding this trope, since the movies could accurately be considered one hugely long film that's simply been chopped into manageable-length chunks. In many cases, what appears to be a What Happened to the Mouse? is resolved in a later movie. But sometimes, the Compressed Adaptation doesn't allow for it.
People who have not read the books may wonder as to why Barty Crouch Jr. from Goblet of Fire does not make a reappearance in later films after Azkaban sees a mass breakout, and other significant Death Eaters like Wormtail and Bellatrix are clearly identified. He'd be easy to notice, given his loyalty and insanity matched only by Bellatrix. Obviously, of course, it would create a plot hole for Fudge's denial of Voldemort's return in Order of the Phoenix if Barty did not receive the Dementor's Kiss as he did in the book.
One of the worst examples of this trope comes in the last two movies. Just like in the books, the first Deathly Hallows movie plants unsettling clues about Dumbledore's backstory and family. The second movie never explains this in the slightest, despite a full history being given in the books.
Crabbe. He disappears from the last film entirely. The filmmakers did this because his actor was arrested on drug charges, but no mention is given to him at all in the film, leaving question as to why Goyle is seen without him, which had only previously happened in Prisoner of Azkaban.
A bit more literally, the fate of Peter Pettigrew is never mentioned in the seventh film, nor is it addressed in the eighth, leaving movie fans to wonder "What happened to that rat?"
In the 2010 remake of The Karate Kid, when Dre and his mother move into their apartment in China, Dre meets a blond boy who befriends him. You can see him cheering on Dre alongside Dre's mom and the Love Interest at the final tournament. He still makes no appearances between his initial introduction and appearing at the tournament, making many wonder where he was, as well as causing some mild surprise at seeing him appear again.
He seems to be an Expy of the neighbour in the original film, who makes friends with Daniel based on Daniel's assumed "cool" and knowledge of "karate." When Daniel gets beaten up at the beach, the neighbour loses interest. Likewise, when Dre gets beaten up in the park, the blond kid, who is also friends with the bully, stops talking to him. I always assumed the blond kid was at the tournament to cheer on the bully but switched allegiance when Dre started winning.
In Piranha 3D Derrick's assistant Andrew vanishes just before Derrick's boat hits a rock and begins to sink. Presumably he is eaten by the piranha but his disappearance is weird since every other named character with lines who dies does so graphically on screen. According to Word of God he was also supposed to get a graphic death (specifically his nose being bitten off) but the scene was cut due to budget limitations. The scene is in the Blu-Ray bonus features (unfortunately only half finished).
Whatever happened to Pugsley the Iguana in The Terminator? Did Sarah ever miss him? It's a safe assumption that either Sarah returned to her apartment to clean up/tie up loose ends, or that Pugsley ran out the door after the Terminator busted the glass. Also, the German Shepherd at the end of the first film—was it Max (11 years on, he'd be pretty old) in T2?
Tim, the guy who went with John to the Galleria Mall, falls off the edge of the planet after the T-1000 shoves him out of the plot in Terminator 2: Judgment Day.
In Death Wish 3, Kersey's friend leaves in the middle of a town-wide gunfight to reload his zip gun. He doesn't appear again. He's probably deader than a doornail.
In Paranormal Activity 2, the family pooch is dragged off screen and knocked unconscious; she survives, and the family takes her to the vet to recover. You never see her again or hear about her death, even in the scene set three weeks after she's left there.
In the theatrical cut at least, Prince John's first wife disappears after the scene which establishes she has been displaced by the French princess, which France can use as a pretext to go to war. John says he will ask the Pope for an annulment, but that's all the film gives on this matter.
After King Richard dies, Robin and his group head back to England. The rest of the English army (hundreds or thousands of troops) are left behind in France to continue the war. They are never mentioned again. What makes this incredibly jarring is that near the end of the movie the French invade England with a sizable army. How is this possible if they are still at war at home? It's like the screen play completely forgot about them, and the audience is expected to as well.
In Mortal Kombat: Annihilation Nightwolf tells Liu Kang he must pass three tests before he can defeat Shao Kahn. The first test is courage, which apparently involves having a hatchet thrown at your head to induce a "dream-state." Presumably the second had to do with Jade, given the convenient timing of her entrance. As for the third...?
Vertigo's Midge vanishes about half-way through the film. She does appear in the alternate ending where she listens to a radio report describing the pursuit of Gavin Elster across Europe when Scottie enters and they share a drink together.
In the National Geographic's The Last Lions Ma-di-Tau leaves her prideland choosing to spare her cubs from the males of the marauding pride. When negotiating with the pride later, the infanticidal males are not mentioned, nor how her cubs are spared from them.
In Faster, Driver's tattoo is touted as some sort of "Warning: Do Not Screw With" sign. The first time it's seen, the sight of it is enough to chase off a 300lb Samoan bouncer. After the film's thirty-minute mark, you neither hear about the tattoo nor see anyone else react to it. We don't even learn what language it's in (though presumably some sort of Samoan dialect), let alone what it actually says.
In The Adventures of Ford Fairlane, there are four bad guys. The Big Bad gets set on fire, the guy that just won't die gets shot in the head, and one of the two punk gunslingers gets shot in the mouth. The other punk gunslinger is last seen fighting Jazz and Sam the Sleazebag, with no further mention of him. An earlier draft of the script depicts him gaining the upper hand against Sam and subsequently being shot to death by Jazz.
In the classic giant ant movie, the opening scenes show the Ellinson girl walking in the desert, catatonic after seeing her family devoured. Later, the elder Dr. Medford waves a jar of formic acid under her nose to test his suspicions. She immediately breaks her catatonia, hysterically shrieking, "Them! Them!" The trooper, FBI agent, and two ant experts hastily deposit her in the physician's arms and flee. She still may be in a strait jacket in the Santa Fe loony bin. Or she's with her aunt and will be fine.
The pilot who reported the flying ants and was put in an asylum. The doctors wanted to release him but the FBI agent told them to keep him there and "We'll call you when he's sane." Twenty years later "Hey, what ever happened to .. uh oh"
An early scene in What Lies Beneath shows Norman and Claire seeing off their daughter Caitlin at her college dormitory. Then Caitlin is never seen or heard from again, even though you can imagine she would be profoundly affected by her mother having a nervous breakdown and getting sent to a shrink, the revelation that her father had an affair with a student and murdered her, and finally Daddy trying to killMOMMY and then drowning in a lake. Was Claire just planning to fill her in over Christmas break?
If Jamie follows the Mystery Team around, how'd she survive the climax unscathed?
The rabbit in Siege of the Dead, apparently they left it in the apartment but do these zombies eat animals and did they leave him out beforehand?
Mr. Hero begins with a plucky reporter mixing Jackie up into a mob plot. She sticks around long after she stops being relevant, only to be grabbed by a mook during the climax. She is not seen again. Maybe she died, but one would think a mob boss being investigated by a reporter would know better. Then again, the mob is never very smart in Chan movies.
In The Medallion, Jackie and his two partners are enjoying some downtime at one of his partners' house. A cooking montage ensues, featuring the character who owns the house and his wife prominently. Shortly, a small strike force attacks the house. The wife tells Jackie and his partners to run while she holds them off, and reveals herself to be Crazy-Prepared. The husband is as surprised as anyone at this, but you never see the wife again.
In Casino Royale (1967), the end title theme says that there are 'seven James Bonds.' Actually, there are eight in the film - David Niven (Bond himself), Peter Sellers (Tremble, codenamed James Bond), Terence Cooper (Cooper, codenamed James Bond), Woody Allen (Jimmy Bond), Daliah Lavi (Lady James Bond), Joanna Pettet (Mata Bond, codenamed James Bond), Barbara Bouchet (Moneypenny, codenamed James Bond), and Ursula Andress (Vesper, codenamed James Bond). However, the scene that accompanies this song, with the 'seven James Bonds' in Heaven, is lacking Terence Cooper, who apparently somehow DIDN'T die in the casino explosion...? Or they may mean Lady James Bond, aka The Detainer; she was last seen before her attempted escape from a second-story bathroom window. Given the extended period of time between her entering the bathroom and the explosion, it can be assumed that she either fell to her death (the first floor IS rather tall), or that she was still trying to descend the drain-pipe during the explosion.
Whatever happened to that nuclear scientist in Thunderball after Bond pushed him off the yacht?
Similarly, what happened to the abducted American astronaut and Soviet cosmonauts in You Only Live Twice?
The Bigger Bad of Casino Royale and Quantum of Solace, Mr White, is revealed at the beginning of the latter to have been captured by Bond, but he escapes. After that, the only time we see him is a short, inconsequential shot of him in a crowd later in the film. In Skyfall he isn't even mentioned.
One particularly bad example was the movie Fantastic Voyage. It features Dr. Michaels, the villain, and the crushed sub, being left behind while the other characters go back to their normal size, despite the fact that Dr. Michaels for some reason doesn't. Isaac Asimov wrote a novelization of the film that corrects this.
Mexican Masked Luchador films are not known for rigorous plot construction, but El Santo Y Blue Demon Contra Dracula Y El Hombre Lobo has a particularly bad example of this trope. At the end of the film, the luchador heroes and Santo's girlfriend discuss what to tell the little girl character about her horrifying ordeal when she wakes up in the morning. They decide to tell her it was just a bad dream. Which, yeah, that'll work... at least until she wonders where her mother is, and they have to tell her that she had been transformed into one of the living dead, and (the film implies but does not directly state) sent to her eternal rest after the destruction of the two titular monsters.
In Sleeping Dogs, as Smith is brought into the police station, he recognizes the man who earlier paid thugs to commit a False Flag Operation which gave the government an excuse to institute a police state. He calls this man "Jesperson." At first it seems the other man does not know him, but then he comes into his cell and offers him a deal if gives a scripted confession broadcast live on TV. Smith takes it, which allows him to escape while en route and sets the rest of the plot in motion. However, where or how they knew each other before is never revealed.
Judge Dredd. Where did the Rico clones go after they were hatched during the final battle? Central did say they were only 60% complete and they were caught in the midst of devastating explosions, it's most likely that they died.
Close to the climax, you last see Rhonda being tossed out of a car. Her final fate is left unresolved: she is never seen (or even implied to have been) killed, but is not with the survivors at the end. Same goes for Izzy, who is seen crawling or attempting to crawl out of the flipped truck, but you never see him again nor does the movie say if he survived or not.
A group of unnamed students are last seen as The Creeper bears down on them. What happened next is up to the imagination.
What ever happened to the cute old couple? They're last seen standing in the downstairs lobby area, then fleeing upstairs when the infected start breaking through, with Manu having to yell at the frightened old lady to get upstairs. When all hell breaks loose, they aren't seen even in crazy zombie form, not even in the first sequel.
The Asian couple's young son is also seen fleeing upstairs, but he's not seen as an infected, in either of the first two movies.
In Our Gang Follies of 1936, you never find out what happened to the Flory Dory Girl Sixtet, the missing act of the show that Spanky and the gang had to fill in for.
Miracle Mile, a Romantic Comedy set during a nuclear war, is told entirely from the perspective of the protagonist, Harry, which means the viewers never find out anything that happens outside his presence. Early on, Harry is with a group of people trying to escape the city before it goes kablooie, but once he's separated from them you never find out what happened to them. The most extreme example involves a car thief who helps Harry early in the film then goes off to rescue his sister. The thief reappears later in the movie carrying his dead sister while suffering from a gunshot wound himself. He dies before revealing what happened to him.
At the beginning of Young Adult, Mavis and a man end up in her apartment after a first date. The next morning, she abruptly decides to leave town for a few days — before he even wakes up. The film ends before she returns. Was her TV still there? The audience never finds out. It provides a Book End for a scene later in the movie, but then she's in the guy's house.
The Mask. Peggy Brandt, who seems to disappear from the main action towards the end. In a deleted scene, her death is shown: Dorian Tyrell caught her trying to sneak off with her money, at which point he threw her into a newspaper machine. This being "The Mask," her death was cartoonish: an "extra edition" came out of the machine, printed in red ink. Peggy's visibly pained face was on the front page, along with the accompanying headline.
This is changed from the way events happen in the book. In the book, instead of what happens to him in the film, Tommy is offered a place in a medium-security prison, in exchange for never mentioning Blatch again. When Andy confronts the warden about it, the warden says no one knows where Blatch is. When Andy tries to press the matter, the warden threatens him, which leads to their confrontation (much is made of this battle of wills in the last quarter of the film).
Hugo never got his notebook back and it's never mentioned after a while. Did George burn it after all or what?
Fans of Tyrone Power's last film, an unjustly obscure John Ford triptych called The Rising Of The Moon, sometimes ask what happened to the jackass in the final scene — the animal, that is. It wanders out of shot during the police sergeant's final soliloquy. Given that just about everything else in that part of the movie is not what it appears to be, the donkey probably belongs to someone else and is simply headed home. Anyway, the sergeant rises and walks in the same direction seconds later.
In Guy Ritchie's Sherlock Holmes the very end features Moriarty stealing a wireless-control-mechanism (several years before its time). Holmes alludes to this as important, but it is not even given a passing mention in the sequel.
In the film of The 13th Warrior, the King's son is set up to be a secondary antagonist. One of the thirteen warriors even kills one of his henchmen in a duel as a psychological ploy. However after angrily leaving the scene of the duel he's not seen or referenced again.
In Men In Black II, the two Dragons Scrad and Charlie disappear halfway through the film, and are never seen again.
In Heat, Chris drops out of the movie after his wife warns him the police are onto him at the safe house. Did he get caught by the police later? Did he manage to leave the country, as his boss Neil planned to? Did he retire and wind up going legit, or did he have to return to crime? Your guess is as good as anyone's.
The novelization of The Dark Knight Rises implies that he's the last inmate of Arkham Asylum, after the others were moved to prisons. Selena thinks to herself that if he's not there, then he's escaped.
Also, did the Joker just leave that party after Batman dived out the window to save Rachel? Since at this point he assumed that Batman and Harvey Dent were the same person, he probably decided to get out, since his main target was supposedly gone, and unlikely to be surprised again.
In The Ramen Girl, one of Brittany Murphy's last film roles, she befriends a couple American expatriates in Japan. They go as far as to set her up with her new love interest, but both disappear halfway through with no explanation.
Ra's all-child entourage were last seen aboard his pyramid-ship shortly before O'Neil teleports the nuclear bomb aboard to kill Ra. This gives rise to some Fridge Logic, as the movie would have been almost an hour shorter if not for O'Neil's inability to hurt a child.
The film's novelization has the children escape the ship just before the bomb is teleported aboard.
You might remember that librarian ghost who gave just about everyone the willies. It's too bad nothing is said about what happened to her!
Her story becomes a plot point in the 2009 video game.
And what became of Venkman's test subjects? The male subject quit and stormed out, but the female agreed to go on a date with him.
In the Alicia Silverstone/Krysten Ritter vampire-comedy Vamps a major plotpoint is that one of the female leads is dating the son of a infamous vampire hunter. While both father and son remain important characters throughout the film, the vampire hunter's wife vanishes entirely a little over a third of the way through. Especially jarring as not only was she implied to be completely in the know about vampires, she was last seen hypnotised by Krysten Ritter.
The crew aboard the doomed train in Super 8. It's never mentioned what happened to them after the explosion and derailment. Presumably everyone on board the train died in the wreck.
You never learn what happens to Dahlia. At the end of the first movie she is kept alive because she's still Alessa's mother, so she is left to wander the Fog World of Silent Hill (which it turns out the protagonists are also trapped in, though they can at least leave the boundaries of the town). She presumably remains there for the 6-8 years (it's unclear which number is right) between the films and cameos in the sequel, but when the Order and their power over the town is destroyed, it's not shown whether she was released into the real world like the protagonists or not.
Something similar could be considered with Rose, the protagonist of the first film. She also presumably remains trapped in the Fog World between the two movies, and a promotional picture even showed her meeting Heather in the Otherworld (though that scene was cut from the final film). It's not entirely forgotten about, since at the end Harry/Chris goes back into the Fog World to look for her... somehow... but you don't know if she's actually still there, or why she would be when Chris, Heather, and Vincent were released.
Michael's bodyguard Fabrizio turns traitor and kills Michael's wife Appollonia, then vanishes from the movie and is never seen or mentioned again.
In the book he is killed by Cuneo assassins at the end, his death was originally filmed for the film but cut (he was to be shot by Michael). It was also planned to happen in the second film, but was again cut for time.
Wes Craven's New Nightmare leaves it ambiguous what happens to Robert Englund. The last you see of him he seems to have become possessed by the Freddy Entity. It's unclear if Freddy ultimately took over his body to fight Nancy or not, and if he did, whether that means that Heather killed Robert. The ending implies that it was All Just A Script, to create a new prison for the entity.
The trope centeric podcast "Film Sack" refers to this as "The Chick in the Bucket" after viewing Wild Wild West, were Will Smith leaves The Girl of the Week in a Water Tower Bucket, never to be seen or heard from again.
The Amazing Spider-Man reboot plays this example with an actual rodent: Dr. Connors is looking for a reptilian gene sequence that will allow mammals to regenerate limbs experiments with a pair of three-legged mice. He discovers a viable gene therapy treatment and uses it to treat one of the mice before using it on himself; this triggers a mutation that transforms him into the violent, Mr. Hyde-like Lizard. Nobody remembers that a mouse also got the regen-juice until late in the film, when Peter Parker notices a savage R.O.U.S. that has devoured the rest of the test animals. Spidey just leaves it loose in the lab, and the mutant beastie isn't seen again. Though presumably this potential problem would have been solved by Peter spraying antidote over all of New York
Breaker Breakerends suddenly right after the climactic showdown between Chuck Norris' JD and The Dragon Strode. Do you get to see what happened to the other townsfolk after the truckers' rampage destroyed Texas City? Nope. Do you see what became of Arlene and her son? Nope. Hell, you don't even get to see if Strode is dead or just unconscious. A brief scene suggested that Big Bad Judge Josh was killed when one of the truckers crashed through his bedroom, but the scene is so badly shot, you can't even tell if the truck even hits Strode, and you don't get so much as a Dead Hand Shot as confirmation.
In Jack the Giant Slayer Jack's uncle is never seen again after Jack joins the king's men to climb up the beanstalk.
In Demolition Man, you never do find out what the three seashells are for.
Oblivion: Jack 52 gets to grow old with Julia. What happened to the Victoria 52 that the audience saw, and the other 50+ Jacks and Victorias that presumably must be out there somewhere?
In Fellini's film La Dolce Vita, the setup for the famous "wading in the fountain" scene was that Sylvia sent Marcello around the corner to an all-night market to buy milk for a kitten she found. He returns with a bottle of milk, but no bowl to put it in, and the viewers never find out if she took the kitten home as planned.
The feisty old British lady driver in the 1953 film version of Henry Kuttner's SF classic The Twonky. You want her to live, but she's not mentioned in the last scene. Since Dr. West ends up in the hospital with a few broken bones but otherwise okay, maybe that's what happened to the driver. She did, after all, get him to the hospital as promised!
In Star Trek Into Darkness, the two security officers that Kirk, Spock and Uhura bring along to arrest Harrison vanish by the time he surrenders, and it is not mentioned whether they survived the fight with the Klingons. According to the novelization, they didn't.
Hafiz (Colman) has a little dog who accompanies him to the Beggars' Mosque and apparently goes off on his own nightly adventures. At the end of the film, Hafiz is exiled from Baghdad, sent to the real province of Hassir, where he'll be a real prince. But the little dog is not seen. A good-sized caravan of camels and wagons appears behind Hafiz and Jamilla, obviously holding their belongings and furnishings for their new home: you want to think the dog is just safely stowed in a carrier.
Likewise, you don't see what happened to faithful Karsha. No doubt she was brought to the royal palace in style, to be Marsinah's servant and friend forever.
In You Got Served, right after the opening dance battle, two girls by the names of Toya and Kiki offer to join the dance group, and are accepted. You see them with the group on their next two dance battles, but after the second battle, they completely vanish from the movie and are never seen or even mentioned again.
In The Lone Ranger Cole is the only villain who dies on-screen. Cavendish takes a speeding train to the face off-screen, so unless he really was a Wendigo (or at least Robert Carlyle's character from Ravenous) it's pretty safe to assume he's dead too. However, Captain Fuller is last seen jumping from said train into the woods (a feat repeatedly shown to be survivable in the film), and is never seen or mentioned again.
Raiders of the Lost Ark. One of the Nazi agents in Cairo is an Egyptian man who wears an eyepatch and has a highly intelligent pet monkey. The monkey is eventually killed by eating some poisoned dates that were intended to kill Indiana Jones, but after the man poisons the dates he disappears and is never seen again.
In Phoenix Wright: Ace Attorney, there is a scene where Maya and Phoenix sneak into the boat caretaker's hut and find a note detailing how he framed Miles Edgeworth for murder. As they read it, an unseen person tasers them unconscious. When they wake up, they find that the note is gone. Those who played the game would know that the person who attacked them is Manfred von Karma (the game makes no secret of this fact, as the attacker electrocutes the two head-on). Presumably the attacker's identity was hidden to make it a surprising reveal later, but the film just sort of forgets about it. Subverted with the evidence that Redd White murders Mia over. In the game, it disappears and presumably was stolen back by Redd. In the movie, it turns out to have been hidden in the Thinker Statue Larry gave Mia, discovered by Phoenix in the nick of time to stop von Karma.
Red Lights left many plot threads dangling. Did Buckley call himself all those times with his powers and not know it? Was he responsible for the strange things going on at Silver's office, and were the apparently possessed people there stooges, or did he unconsciously influence them? Additionally, while Silver's supposed "thought transference" was explained, they never said anything about the "thought photographs" which he produced that Shackleton said had "no scientific explanation." Of course that could have been faked too- you don't see how though.
The Master: Freddie assaults some police officers coming to arrest Dodd, and gets arrested himself. Dodd gets sentenced and released, but you don't see how Freddie's was resolved; he simply turns up at the house. It could be he was just out on bail, but nothing more is shown, and it's quite unlikely charges of assaulting police were simply dropped, as those tend to get taken very seriously.
The Warriors: Who was that talking on the phone to Luther at certain points in the film? This person is never named or even ever heard speaking, and all the viewers learn is that whoever it is must be in on the conspiracy against the Warriors somehow ("We set, all right") and is someone Luther knows on a fairly personal basis ("Yeah, you take care of yourself"). Many fans have speculated that it must have been some representative of the New York Mafia - a group that would naturally want to disrupt the alliance of all the street gangs and might have paid off Luther to make sure that didn't happen.
In Chungking Express, the female lead (or at least the lead in the first half of the movie) is engaged in apparent black market dealings with a group of Indian expats, a plot line that eventually disappears.
Mister Lonely: The rest of the Impersonators' fates are unknown, after Marilyn commits suicide and Michael leaves.
What happened to Goldsmith Pictures and Flugleman after the Amigos were fired? The Three Amigos were apparently their main franchise.
Near the end, Dusty Bottoms throws a knife and pins one of The German's two henchman to a pole by the sleeve of his coat. The last seen of him he's still pinned to the pole. It's never shown what happened to him.
In Cowboys and Aliens, the heroes encounter a huge overturned riverboat miles away from any body of water. It serves as a temporary shelter, but after they move on, no mention is made of how it got there or why.
In War, Inc., Hauser is shown milking a cobra for its venom. When Yonica enters the room, he throws the cobra into the corner to prevent her from seeing it. A second later, the cobra is gone and not mentioned again.
The dog at the beach in Godzilla (2014). Its fate is uncertain, though it does at least escape from the beach when the tsunami hits.
Averted in Titanic. The fate of a surprising number of minor characters and extras can be known by either reading the script or paying very close attention to the background, or by reading a historical book if they're real people.
No indication is made of what happened to the Juggernaut after he got knocked out shortly before Phoenix began killing everybody on the island.
Nothing at all is stated as to what happened to Pyro, either having been captured or killed.
In X-Men: First Class, the Hellfire Club is never mentioned or seen again after the early sequence where CIA operative Moira MacTaggert (who is investigating it with a colleague) sneaks in and witnesses Emma Frost and Azazel reveal their powers in front of an American general.
Mystique is shown impersonating William Stryker at the end of the movie, but what she did with the real Stryker is unclear.
Magneto doesn't mention Riptide's death alongside the other deceased Brotherhood members, although Mystique does find a autopsy file on him in Trask's office, indicating that he was killed in-between films as well.
Angel is the only X-Man killed in the Bad Future not to appear in the new timeline. In fact, he doesn't appear in the movie at all. Even future Beast, who debuted in the same movie as Angel, got to make a cameo!
The Inuktitut-language Atanarjuat is littered with Vanishing Wives. Early on, Oki's two sidekicks marry sisters. The scene is presented as a one-off joke; the wives are never seen or heard from again. More seriously, when the title character's brother is killed, he leaves a pregnant widow. The film promptly forgets she ever existed.
Sam and all the other human characters in Transformers: Age of Extinction. Despite being the main focus in the first three movies, there isn't a mention of them anywhere in the fourth one. Instead there's an entirely new cast of human characters to replace them.
Just before the final shootout of Lethal Weapon 4, the Chinese General shoots and kills two of the Four Fathers while Ku and his brother attempt to flee, but whatever happened to the other Four Father while the other two were being shot?
When Cholo DeMora in Land of the Deadis bitten and infected by a zombie he goes back to Manhatten to settle his score with Kaufman, leaving his buddy Foxy behind. The audience never learns what becomes of Foxy or if he survives.
In Notting Hill, William Thacker has a series of disastrous blind dates. However, the last one is a seemingly perfect match for William. After her scene, no mention is ever made of her again.
For the first third of Film/Chef!, Scarlett Johansson's character, Molly, seems to be the female lead, but when the action switches from California to Miami she vanishes from the movie. No affront to realism, just to our expectations. The cameos by Dustin Hoffman and Robert Downey Jnr do advance the plot (such as it is) but we expect Johansson's character to be developed.
At the beginning of 7 Zwerge - Der Wald ist nicht genug, two kids report a fire to Speedy. He makes them promise to keep it going until he gets there because he hates it when he responds to a fire only to find that it already went out before he arrived. The kids agree, but before Speedy can get to the fire, he is recruited into the main plot, and the fire is never heard about again. One wonders how long they managed to keep it going.
In Dracula Untold, despite the signs that it would signal doom for the world, Dracula gives into bloodlust and ends up freeing the Elder Vampire....who then disappears from the film, until the epilogue more than 500 years later, at which point he says that the "games begin".