Something like that happened to me when we went to see Spiderman II at the local IMAX. The sound and video started getting a little out of sync. I needed to go to the restroom, which was upstairs by the projector room. The projector is pretty cool--cool enough that they have a big window so you can see it. In this case, I walked by and saw the film pouring out of the side of the projector into a huge pile on the ground. IMAX film is huge--the reel was at least three feet across, IIRC. Anyway, it was quite a mess.

Needless to say, the movie was stopped within a couple of minutes, and we all got passes to come back later. It was a bummer.