Ichabod and his Horse, probably the audience watching as well, get one of these in The Adventures of Ichabod and Mr. Toad. After long build-up to the arrival of the Headless Horseman himself, a false alarm makes the two burst out in laughter, putting everyone's minds at ease. Then at 4:26, that damn cackling starts. Oh Crap Mode for everyone.
Mr. Potato Head does it on Toy Story right before a flying RC slams into him.
As does Woody when Buzz explains that revenge is something that isn't encouraged on his planet... then clarifies that they're not on his planet.
As does the cast, when they hear the new puppy barking at the end.
"Wait a minute. I just lit a rocket. Rockets explode!"
Woody was in Oh Crap mode from the moment he and Buzz were thrown into Sid's car to the moment he finally convinces Buzz to escape with him, then he gets it back briefly when the milk crate with a full tool box on it is about to land on him.
Buzz gets one as he learns the hard way that no, he really can't fly.
Syndrome does it when Mr. Incredible tosses his car at him.
One of Syndrome'sMooks flashes one as well, just before his velocipod slams into the side of a mountain.
Another mook has this as well later in the film. They're all joking about the Omnidroid wrecking the city, and one pops a champagne bottle. Their expressions change real fast when it turns out Mr. Incredible caught the cork.
Not to mention Mr. Incredible's epicOh Crap moment in the final battle when the Omnidroid sees him holding the remote. It's hard to resist shouting "SMAAAAAAAASH" when he gets stomped on.
To be fair enough, that's because he placed the blame on them for Mufasa's death. Since Scar was the one who killed him by shoving him to his death, the hyenas weren't thrilled about being blamed by their master who was responsible for said titular character's demise. Yup. Shifting the blame for killing his brother on his own Quirky Miniboss Squad is never a good idea.
Oddly enough, this was only shortly after he brought one out of them, with an aside Death Glare upon realising they hadn't finished Simba off.
And before that, when right after slapping Sarabi to the ground, and notices a rather angry looking Simba above them watching the whole thing.
Before that, the hyena trio has chased down Simba, Nala, and Zazu with intention of eating them. Simba plants his feet, arches his back, takes a deep breath, and delivers...a cute little-boy roar. The hyenas smirk and dare him to try that again. Simba takes another deep breath as the hyenas grin, and...A THUNDEROUS LION'S ROAR splits the air. The hyenas have just enough time to have an Oh Crap expression before Mufasa's paw slams them into the ground.
Mufasa himself gets an Oh Crap when he realizes Scar, whom he trusted implicitly, is going to push him off the cliff.
Likewise, Dr. Facilier in The Princess and the Froglets out a deliciously desperate "FRIENDS!" and looks like he just crapped his pants when the evil spirits come for his soul.
In Monsters, Inc.., Mike Wazowski gets one when Roz asks about his paperwork (not finished), and he doesn't have time to complete it before his date.
Roz: Your stunned silence is very reassuring.
It helps that Mike is almost entirely (wide) eye and (slack with horror) mouth.
Employee: 23-19!! 23-19!! (CDA decontamination teams burst out of the bathroom stalls) George:Ohhhh dear.
George's assistant gets a very satisfying one when George decides he's fed up with the little twerp, and 23-19s him into the human world.
Horton Hears a Who! has the Mayor do a split-second, but wildly stretched, take once he realizes the stapler he was aiming at the portrait of the Council Chairman bounces off and flies back toward him... landing on his face... and staples anyway! In fact, many characters in this film have classic cartoon expressions by the nature of its original illustrator.
Red gives a loud scream seconds before her speeding mine cart hits a dead-end on the tracks.
Red's reaction to the phone call she makes to Granny in Japeth's shack. Her wide-eyed look as she says, "Mr. Goat, my granny's in trouble! I've got to find a way around the mountain, fast!"
In the treehouse, Red hears a glass window being broken. She rushes over to her granny's store, and finds that someone has thrown a rock through the front window with a very threatening note on it. Also, the store owner next door is putting up a sign that says "Out of Business".
He's chasing Red's cloak, unaware that it's being flown by hummingbirds. But he doesn't know that until he grabs the cloak, at which point the camera pulls back and reveals that he's frozen in mid-air past the edge of a cliff. He remarks, deadpan, "OK. Not cool."
In the mine cart, when he realizes that Twitchy has lit a stick of dynamite. Up to Eleven after attempting to get rid of it only ignites the rest of the charges stored in back.
"OH SCHNITZEL!" when a giant redwood tree he was trying to cut down starts to fall towards him. He has a Deer in the Headlights moment.
Many characters in Kung Fu Panda have these, since martial arts sequences are the highlight.
By far the most epic would definitely be the one worn by Tai Lung when he realises that, yes, Po knows the Wu Xi finger hold. Skadoosh.
Close second also goes to Tai Lung in his battle against Po. In that split-second before Po's ass comes down on his face. Third to Shifu, when he realizes he's really stuck with Po. Complete with Eye Twitch.
"Tai Lung is free!" Pretty much everyone in that scene gets this look at least once. Except Tai Lung of course.
Happens to the entire heroic cast during the final battle of Kung Fu Panda 2 when they notice that Lord Shen has a lit cannon pointed straight at them. Then happens to Shen himself when Po learns how to redirect cannonfire.
Earlier, during the rickshaw chase, Boss Wolf gets this expression when he turns around to see Po about to slam into him, complete with a terrified scream.
1 gets a good one when he first sees 2 return. After dying and being sewn onto the Seamstress.
In A Bug's Life, Francis the ladybug is confronted by the two flies he'd been heckling earlier. They ask him to repeat what he said to their friend, "Thud." Francis's well-deserved "oh, crap" hits the instant he hears Thud land behind him.
The expression Flik gets when he realizes his "Warriors" are actually circus performers.
In the new DTV Wonder Woman movie, she gets an "Oh Crap" moment during the climactic final battle with Ares... saying "Oh Crap."
The setup is what makes it awesome. When we first meet Steve Trevor, he uses the expression, and the Amazons decide it's proof of how vulgar men still are. Diana gives him a death glare every time he uses it. Then, when... well, I won't spoil it for you... Diana can only stare and go, "Oh, crap."
Ares gets one when his second to final scene echoes his own son's death, as the killer of his son's daughter (say that ten times fast) Wonder Woman LOBS his head off in exactly the same way.
The Efrafan warriors have an Oh Hraka moment when the dog charges over the hilltop to maul them at the conclusion of Watership Down.
Monsters vs. Aliens has a slew of these moments, for both the good guys and the bad guys. The best is a string of Oh Crap moments for Gallaxhar when, after he imprisons Ginormica in a force-field cage, she (1) pries her way out, then (2) busts through a series of thick doors he tries to seal her behind, and, when he finally races through air vents too small for her to enter, (3) keeps punching holes in the vents that nearly squash him.
Batman: Under the Red Hood: Batman's look of shock when he processes the audio of Red Hood's taunt, and discovers that the last word was "Bruce", indicating Red Hood knows Batman's identity.
Black Mask saying "Oh, hell," as his reaction to seeing the Red Hood aim a rocket launcher at him.
We also get a nice "Oh crap"-look from the Joker after the Red Hood captures him and the Joker sees him draw out a crowbar.
Similarly, Red Hood says "crap" early in the final fight, when Batman attacks him with explosive pellets.
Felicia, Ratigan's fat, spoiled cat in The Great Mouse Detective, sort of has a double one herself. First, after Basil, Dawson, and Olivia rescue Queen Mousetoria from being fed to her, Felicia hears barking and turns around to find Toby coming after her. She screeches and runs for dear life. Second, after being chased by Toby for some time, Felicia climbs up on a wall, sneers at Toby (dogs can't climb very well), sticks her tail and her butt in the air, and leaps over to the other side of the wall, only to get attacked by guard dogs!
Cody in The Rescuers Down Under, gets a spectacular one as he falls off a cliff after freeing Marahute. Thankfully, she catches him.
Also the scene where Mc Leach escapes from the crocodiles to the apparent safety of a floating log. Then he looks up and sees his sidekick mournfully waving good-bye to him from the shore. He turns around and sees the log is about to go over a massive waterfall.
Finding Nemo: When Nemo and Dory discover that the light they're following is an anglerfish's lure: "Good feeling's gone."
When Bruce smells blood in the water: INTERVENTION!!!
When the whale approaches:
Marlin: "Just as well. He might be hungry."
Dory: "Don't be silly. Whales don't eat clownfish, they eat krill."
The Glass Slipper has been destroyed, the Evil Step-Mom is just beginning to gloat, when Cinderella pulls the other slipper from her pocket. Closeup on the Step-Mom's face, and its near-perfect "Oh, Crap!"
Moments before this, the prince's servant has one when the slipper breaks. Even earlier, Cinderella has one when her stepsisters destroy her dress. And when she hears the clock strike midnight...
Jiminy Cricket has this moment when he finds out the true purpose of Pleasure Island.
Jiminy: Boys? So that's what...PINOCCHIO!!!
Also Pinocchio himself when he first encounters Monstro the whale.
"I'VE BEEN DOUBLE-CROSSED!!!"
Vector from Despicable Me when Gru storms his hide-out in order to get the girls back. "He... he punched my shark!" An earlier scene had an obnoxious carny put on a horrified face when Gru's response to the carny making fun of Agnes is to take a Death Ray to his target-shooting game.
In The Tigger Movie when the avalanche is about to start.
Piglet Is that a rumbly in your tumbly, Pooh?
Pooh: I don't think so, Piglet.
The title character from Sintel when she realizes that the dragon she just killed were the one she wanted to save in the first place.
Mickey Mouse in Fantasia when he sees that the broom he just chopped to bits has multiplied into hundreds of brooms. Note that his drooping hat stood right back up when he saw them.
The dinosaurs in the Rite of Spring segment when they see the Tyrannosaurus-Rex.
The boys do this when they find out Cartman forgot to disable the alarm and they have been detected by the army. Kyle even spouts "Oh shit!"
Robin Hood gets cornered by the Sheriff of Nottingham wielding a fiery torch in Robin Hood
The Queen of Hearts when Alice grows giant size in Alice in Wonderland, not even having time to finish her catchphrase. Gets turned around when Alice suddenly realizes she's started shrinking back to normal size while she's in the middle of telling off the Queen of Hearts, and Alice is the one to have an Oh Crap moment.
The Horned King in The Black Cauldron gets two. First, his expression of triumph becomes disbelief and denial when Gurgi's sacrifice breaks the Cauldron, causing his undead warriors to become lifeless again. Then Taran pushes the Horned King near the Cauldron, and the Horned King starts freaking out when the self-destructing Cauldron starts drawing him into it. He barely has time to let out a Big "NO!" before the Cauldron turns him into dust and sucks him into it right before it explodes.
A Goofy Movie has one for PJ when he's leaving the principal's office, dreading his father's punishments, and one for Max when he and Goofy (oblivious) are about to fall off a waterfall. The earlier one is effective despite the fact that PJ is a Nervous Wreck, because he has noticeably different behavior from when the thing he's anticipating isn't inevitable.
Ariel has one when King Triton discovers her grotto and comes out of the shadows. She has an even bigger one when she blurts out "I love him!". She and Sebastian (and most likely the audience as well) knew things were going to get really ugly.
And a bit before that, Sebastian when he accidentally reveals that Ariel has fallen in love with a human to the king.
Sebastian: I tried to stop her, sir! She wouldn't listen! I told her to stay away from humans! I told her humans were bad! They are bad, they are—
Triton: Humans!? What about humans!?
Sebastian: Humans? (chuckes nervously) Who said anything about humans?
Near the end of Cats Don't Dance, Darla Dimple gets a huge one when she accidentally blurts out that she flooded the studio to frame the animals over the boom mike for her boss and all of Hollywood to hear.
A wonderful example is in Wreck-It Ralph, when Ralph goes to try playing Hero's Duty. He's all excited as the game warms up... And when the door opens to reveal the clouds of deadly Cybugs, his face drops to a priceless Oh Crap.
Ralph: Sweet Mother Hubbard...
Near the end, Cybug!Turbo gains control of himself just long enough to do this as he's pulled into the beacon. Dying as Yourself is NOT always a good thing.