The Lord of the Rings: The Two Towers
The moment when the flag is flown was not planned. It was so windy that day and the flag was apparently not tied very well. It stayed in the final cut as it was a beautiful metaphor for everything that would happen afterward.
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.