The Dark Knight
The production had only one chance to do the hospital explosion and the scene was going normally until the switch to detonate the bomb failed. Heath Ledger stayed in character and continued to push buttons until finally, it worked. It was an unexpected comedic moment in an otherwise tense scene.
I live near very near to LA; I know people who work in the film industry. Around here, a lot of people would have firsthand knowledge of that sort of thing, so it wouldn't be unusual to hear from someone who knows something such as that.