The Dark Knight – Explosive Mistake
Heath Ledger as The Joker in The Dark Knight is one of the all-time great villain performances, and it turns out that Ledger made more than one unscripted acting choice that made it into the film. During a scene in which The Joker is blowing up a hospital, he uses a device to ignite the explosives. Unfortunately, the explosion didn’t go off in time. So Ledger, staying in character, pushed the button a few more times until the building finally goes up in flames.