Crowd Panic

Someone shoots, crowd panics. Someone says there's a bomb in the building, crowd panics. Usually found in comedy / cop movies.

No one in the crowd ever trips or gets stuck.

When someone besides the group of Living Prop guys do it, it's a Mass Oh Crap.

Film

 * Lampshaded in Last Action Hero
 * The Naked Gun 2 ½, where Frank Drebin tries to evacuate a crowd in orderly fashion.
 * Batman, the movie of the 1960s series. "Some days you just can't get rid of a bomb."
 * Specifically: Batman runs with into a restaurant with a Cartoon Bomb and urges everyone to flee for their lives. The crowd promptly panics and escapes (except for two ladies who ignore Batman and keep eating their lunch as if nothing had happened).
 * Quantum of Solace when an escaping QUANTUM agent shoots a random girl.
 * D.E.B.S. When Lucy Diamond is spotted at the Endgame celebration, the crowd panics and flees.
 * King Kong (1933). When Kong attacks the native village while searching for Fay Wray, the natives leave in a justifiable hurry.
 * Blazing Saddles. When Mongo first arrives in Rock Ridge, a crowd in the street sees him, panics and runs away.
 * Dogma: After Bartleby breaks Officer McGee's neck.
 * Damnatus: Complete with bell-ringing doom prophet.
 * Invoked in Conspiracy Theory Mel Gibson's character is followed into a movie theater by bad guys and shouts that there's a bomb under his seat in order to escape in the resulting panic.
 * When the reporter on the airplane manages to get the fact that terrorists have seized control of the air traffic control systems of the airport in Die Hard 2 on the evening news, everyone in the airport panics. This mainly serves to ensure that the cops can't get through the crowds to attempt to do anything about it.

Literature

 * In Artemis Fowl: the Lost Colony, after the first demon appears in the street, it disappears. The crowd "froze", but when it disappeared, the crowd "unfroze violently".
 * The ending of the Twelfth book of A Series of Unfortunate Events implies this.

Video Games

 * In The Godfather: The Game, whenever you get seen with a gun... or someone starts shooting... or you crash your car into something... or some other stuff, the passersby quickly start running helter-skelter.
 * In the entire Hitman series, the civilian NPCs panic and flee at anything vaguely violent or seeing someone with a gun in a non-military context. They'll also run if they find evidence of your handiwork, i.e. corpses or in some cases bloodstains.
 * The Assassin's Creed series have this, normally when you kill someone in full view of them. Oddly, people will cheer you on when you fight with the guards, but flee in terror when you kill one.
 * Prototype had this, though normally someone won't start panicking until you pick up cars, kill people, or use your offensive powers.
 * The Getaway: People would freak out and run during the first half of the game if you were seen with a gun in public, and just like they would in real life, at least some of them call the cops. Less of an issue in the second half, as you're playing a plainclothes police officer and usually accompanied by some uniformed colleagues.

Web Comics
"Ellen: Dammit, if the goo starts to eat people I hope whoever that was is the first to go..."
 * Schlock Mercenary has it as part of a plot to blow up a building without any innocent casualties. They stand still on the initial command to evacuate, and thus need a little nudge.
 * In El Goonish Shive when the Omega Goo attacks a blond girl calls for a crowd panic.