The Princess Diaries
When Anne Hathaway talks to her friend while climbing the steps in the schoolyard, she accidentally slips and falls. Some people in the cast and crew wanted to go and help her, but she decided to continue the scene by laughing at her clumsiness and continuing the conversation she was having while in character.
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.