In the second act of 5 Centimeters per Second, Kanae suffers greatly due to her inability to tell Takaki that she loves him, not knowing as the audience does that Takaki's own inability to communicate his feelings for Akari is causing their relationship to unravel.
As seen on Missed Him by That Much, the audience of An American Tail knows that Fievel is alive, but his family doesn't, making the scenes in which they barely miss spotting each other that much more heartwrenching, and expounding the payoff when they do reunite.
In The Jungle Book, Bagheera is trying to convince Col. Hathi to help him find Mowgli before Shere Kahn does. Hathi refuses, saying that "Shere Kahn isn't within miles of here", unaware that the tiger is eavesdropping in on the whole conversation.
One of the main plot points of Kung Fu Panda 2 is Po's personal quest to find out what happened to his biological family. Their fate is known to the audience right from the beginning, leaving us only to wonder what Po's reaction will be. Used again in the ending, where we are shown that many of the pandas are still alive, but Po is left unaware until the sequel.
Ariel: It's too dangerous in the sea! Melody: How should you know?! You've never even been in it!
Pretty much all of Mulan in between Mulan disguising herself as a man to take her father's place in the army and the reveal of the Huns' attack, during which the movie is a more lighthearted run off of both the humor and the tension that comes from everyone around Mulan being unaware that she's really a woman. The two songs during that part, especially, show this off — "A Girl Worth Fighting For", where the other soldiers pull Mulan into a conversation about the women they want to marry, and "I'll Make A Man Out Of You," which speaks for itself by the title alone. This lyric particularly drives it home:
Did they send me daughters When I asked for sons?
An instrumental plot element in The Lion King is the fact that for most of the second half of the film, Simba is unaware that it was actually Scar who killed Mufasathough the audience sees this happen onscreenand therefore is convinced that he himself is responsible for his fathers death.
The Powerpuff Girls Movie has a middle act that basically runs on this trope. The movie makes it very clear to the viewer that while Jojo may seem sympathetic to the girls, his intentions aren't good - not to mention the fact that if you've seen any of the show that this movie is a prequel for, you already know he will become the villain Mojo Jojo in due time. This knowledge makes it very stressful to watch the girls trust him wholeheartedly and help him complete a mysterious project that they believe will help make the town a better place. The irony is especially clear during a scene where the audience hears dialogue of the girls reassuring the Professor that things are going to get better... just before you see Mojo putting the final pieces of his evil plan into place and laughing maniacally.
Near the climax of Shrek 2, the Fairy Godmother sings a rousing rendition of "Holding Out For a Hero" as part of her cynical plan to get the sniveling Prince Charming to kiss Fiona, whom she thinks has been enchanted with a love potion. What she doesn't know is that the real hero, Shrek, is busy Storming the Castle, making the song about as deliciously ironic as it comes.
Sleeping Beauty: Prince Phillip and Aurora meet each other in the forest and each assumes the other is a peasant. Both express drama over not being able to be with the other because of this, since they themselves are royalty. But the audience knows that they are both royalty and have been betrothed; not only can they be together, but they will be together.
In Tangled, Rapunzel becomes the center of attention during the celebration in honour on the missing princesses' birthday. The audience already know she's the lost princess. There's even a short scene with Rapunzel staring at a mosaic of the royal family, particularly the baby princess, unaware she's looking at herself.
In an early scene, Dracula is attempting to leave his coffin, as Abbott and Costello's characters are delivering it to a house of horrors. The audience sees Dracula perform a number of actions in his attempt to leave. Costello's character sees the results of Dracula's actions, but never actually sees Dracula himself until much later in the scene. Abbott's character sees nothing, and mocks Costello's character for his superstitious behavior.
Another scene puts Costello's character in the same room as Frankenstein's monster, while being completely oblivious to the monster's presence. The two of them get closer and closer with Costello's character remaining completely oblivious, culminating in him sitting in the monster's lap while remaining unaware.
Aint Them Bodies Saints: Patrick romantically pursues Ruth, not realizing that she was the one who shot him when he and other police officers arrested her and Bob for armed robbery. Bob took the fall for the whole thing.
A lot of the things characters in Andhadhun do and say based on the incorrect belief that Akash is blind qualify, but especially Simi and Manohar's attempts to cover up the crime scene without tipping off Akash, which is heavily Played for Drama.
April Showers: In a flashback, April tells Sean "It's not going to be the same without you", referring to his upcoming graduation. By this point, the audience knows that April is going to die in the school shooting whereas Sean will survive.
Marty and George concoct a plan wherein Marty will intentionally start harassing Lorraine, so that George will have his opportunity to come in and act as if he's intimidating Marty into leaving her alone, thus wowing Lorraine with his awesomeness. Unforeseen hitch though; Biff Tannen actually kidnaps Marty and proceeds to very seriously harass Lorraine. However, rather than torpedoing the whole plan, this actually leads to George wowing Lorraine.
"Biff Tannen, I wouldn't marry you even if — even if you had a million dollars!" Which, in the alternate timeline, he had. Several times over. And she did.
Back to the Future is big on this. Consider the 1955 dining room scene:
Lorraine's mother: Why do you look so familiar to me? Do I know your mother? Marty: [looking in Lorraine's direction] Yeah, I think maybe you do. And later... Lorraine's father: He's an idiot. Comes from upbringing. His parents are probably idiots too. Lorraine, if you ever have a kid that acts that way I'll disown you.
When Goldie Wilson, the black busboy in 1955, declares he will make something of himself, Marty declares that, indeed, he'll become mayor. Those who hear this proclamation think it's hysterical.
The Big Hit: Melvin, Cisco, and the rest of their team kidnap Keiko to extort money from her wealthy corporate father when in fact he has just gone broke the very same day.
In Blind Chance Witek can't leave the country when siding with the Party, because he's needed to help quell the protests; but he can't leave when he's a dissident, either, because he didn't want to rat out his contacts and thus was denied a passport. And when he remains uninvolved in either side and is granted the passport, his fated plane explodes right after the take-off.
In The Bourne Supremacy, Pamela Landy and her operatives in the CIA are busy rushing around setting up various forms of surveillance and tracking in order to hunt down and bring in the rogue operative Jason Bourne, and immediately put a trace on his phone when he calls Landy on her personal phone... all the while completely unaware that at that very moment he's set up a sniper rifle and is tracking their every move from a building directly across the street.
Butch: Hey, wait a minute. You didn't see Lefors out there, did ya? Sundance: Lefors? No. Butch: Oh good. For a moment there, I thought we were in trouble.
In The Chase, many of the television stations covering the chase speculate that Hammond planned to kidnap Natalie Voss because she's the daughter of the richest man in California. It was actually a completely spur-of-the-moment kidnapping after Hammond was spooked by two police officers walking into the same gas station, causing him to take the only other customer in the store hostage (who just happened to be the daughter of the richest man in California).
Having not met him yet in this continuity, everyone (the police, the mob, and even Batman) disregarded the Joker as a threat and believed the mob was more dangerous. The audience, however, knew better than that, though even they didn't anticipate this version of the Clown Prince of Crime to be as dangerous as he was.
Exit Smiling is about a theater troupe that tours the country playing a ridiculous Large HamMelodrama in which the heroine has to pretend to be The Vamp in order to delay the bad guy. When Jimmy takes his leave of Violet at the end, he says "I sure hope you get a chance to play that vampire part some day." Little does he know that she did, for him in Real Life, to delay the bad guy in order to clear Jimmy of embezzlement charges.
One scene in Five Came Back, about a plane that crashes in the South American jungle, features a man organizing a search party. He says it's "not likely that they crossed the mountains into the valleys near the Amazon." This is exactly what did happen, because the plane's navigation failed and it was blown off course during the storm. This is also why there's no hope of rescue.
Virtually the entire first Halloween film, and much of the later ones, is simply "Hey! The killer is in the background! And the characters can't see him! Oh, Crap!!"
In Halloween II (2009), Dr. Loomis is making a speech at a press conference for his new book, saying that Michael Myers is dead and will never come back, when at the moment, unbeknownst to him, Michael is beginning his new killing spree.
You learn that there's a dead body in the cupboard of the living room where Rope takes place, but other characters go about having no idea for much of the film.
In a World......: When Fred Melamed tells Ken Marino, who has been bragging about his sexual exploits, to "give her another one for me," neither character is aware that he's talking about his daughter. Yuck.
In In Bruges, Ray's boss, Harry, orders Ray's death because he killed a child, albeit accidentally. At the end (and this is a major spoiler!) Harry believes he's killed a child, and shows himself to be a man of principle by committing suicide. In fact, he's killed a midget, but he's dead before Ray can inform him of this.
Jeanne Dielman, 23 quai du Commerce, 1080 Bruxelles: Jeanne's teenaged son says "Well, if I were a woman, I could never make love with someone I wasn't deeply in love with." What the boy doesn't know, or at least what the audience doesn't think he knows, is that Jeanne is a prostitute who receives callers in the apartment during the day while her son is at school.
Happens repeatedly for tension in No Country for Old Men. Much of the movie is just simply watching what will happen to the characters as they walk into a situation, oblivious to what the audience already knows. And then it subverts the trope by getting those characters out with a hidden ace the audience didn't see.
In Pass the Gravy, Schultz has a prizewinning pet chicken. The chicken is inadvertently roasted for dinner by the neighbor's dimwitted son—for a dinner with Schultz as the guest of honor. Cue several ironic comments made by Schultz as he unknowingly eats his own pet chicken. "It tastes as good as one of mine!"...."They act like it's a funeral!"...."It's my chicken and I'm going to eat it!"
In The Phenix City Story, Albert Patterson states repeatedly that he may be killed for trying to fight the organized crime in Phenix City. The viewer knows either from history or from the prologue that he will be.
In The Right Stuff, one of the early scenes shows Trudy Cooper, wife of Gordo Cooper, airing her fears for her husband's safety as a test pilot to Betty Grissom, wife of Gus Grissom. This was when the two eventual astronauts were test pilots at Edwards Air Force Base. Sadly, Betty Grissom would be the one to become a widow when Gus died in the Apollo 1 fire.
In The Room, Johnny sets aside his problems with his fiancée Lisa to lend a sympathetic ear to his best friend Mark as he complains about a girl he's seeing, unaware that Mark is talking about Lisa.
Used to extremely disturbing effect in Saw. Upon hearing gunshots and screams over his cellphone, Lawrence breaks down, saws his foot off to get free of his shackle, and shoots Adam like Jigsaw wanted in order to save his family, not knowing that they had already gotten free and the screaming and gunshots he heard were from the scuffle following it.
The Halloween example pops up later in Scream (1996) when Randy is watching the infamous scene with Laurie on the TV and he says "turn around, Jamie, he's right behind you". Yes of course the killer is behind him as well. Bonus points in that the actor's name is also Jamie.
The first Spider-Man movie has a scene near the end where Harry Osborn tells his best friend, Peter Parker, about how much he wants to kill Spider-Man to avenge the murder of his father, Norman Osborn. Of course, Parker is himself Spider-Man.
In Star Trek (2009), Kirk and McCoy meet Spock for the first time. In the original continuity, McCoy was the id of the Power Trio that opposed logical Vulcan Superego Spock and on times called him a pointy eared, green blooded bastard. Now:
Kirk: Who was that pointy-eared bastard? McCoy: I don't know, but I like him.
Cochrane constantly snickers at all the things Riker says will happen in the future, when it's his work that will cause it to happen. Although when it finally sinks in he has a minor breakdown, and tries to explain that his motives were much more selfish than Riker seems to assume.
During the historic flight of the Phoenix, Cochrane orders Riker and LaForge to go to warp by saying Engage!. Both Riker and LaForge silently chuckle, as does the audience.
The entire prequel trilogy. You know that everyone with the exception of Obi-Wan is (probably) going to be killed anyway (by their own clone forces!) and that Anakin is going to go evil. This makes around 80% of Revenge of the Sith a near Tear Jerker.
Obi-Wan:[after Anakin takes them through a perilous chase] Why do I get the feeling that you'll be the death of me?
The Phantom Menace portrays Palpatine becoming Supreme Chancellor and Anakin beginning his Jedi training as a happy ending. And it appears to be one within the context of just that film. But if you've seen the original trilogy, you know that these events lead directly to The Empire.
A more traditional example of this in The Phantom Menace is Qui-Gon telling Padme things like "The Queen trusts my judgement, young handmaiden. You should too." However, he (probably) knew that she was really the Queen, so he was likely just messing with her.
Palpatine: Get help, you're no match for him. He's a Sith Lord. Obi-Wan: Chancellor Palpatine, Sith Lords are our speciality.
In Rogue One, Grand Moff Tarkin uses the newly-completed Death Star's superlaser to eliminate the Rebel forces that broke into the Imperial Database archives on Scarif, an act which actually kills more Imperials, including his rival, Director Orson Krennic, who'd just learned of the Death Star's hidden weakness. So Tarkin ends up dooming himself and the Death Star, setting the stage for the Battle of Yavin in A New Hope.
The Truman Show tells the viewers that the main character has unknowingly spent his entire life trapped in a bio-dome being the star of a 24/7 Reality Show. Then we see how some unusual events cause Truman to realize the truth of his reality and plan his escape into the real world.
Valkyrie: During Colonel Stauffenberg's visit to Adolf Hitler's Berghof residence in Bavaria, Hitler praises Stauffenberg for his sacrifices as a soldier and wishes that more of his men were like him. If only there were! At this time, Stauffenberg is planning an assassination of Hitler and a coup d'etat against his regime for its excesses.
Hank McCoy's attempt at a cure on himself appears to work and then fails horribly in X-Men: First Class. When he later uses a variation to rob Erik/Magneto of his powers in X-Men: The Last Stand, it seems to work. And then, rather subtly, it also fails.
X-Men: Days of Future Past: '70s Magneto is the most unsympathetic portrayal yet, while the future Magneto is the first time he's shown as an outright hero. Near the end, Magneto in 1973 attempts to assassinate the president on live television in order to start a race war, and Magneto in 2023, dying from injuries obtained in a Last Stand, regrets that he wasted so many years fighting with Xavier and reconciles with him.
Continuing off the above, Trask sees mutants as a common enemy which can unite all the human race and end the Cold War. In the Bad Future, Trask's inventions have become the common enemy that united all the mutants. Oh, and the Sentinels eventually oppressed almost all of humanity and mutants.
In Yamato, it's cringeworthy every time a character talks about going to Hiroshima, considering what happens to that city just a few months later.