A while back I posted about an app called RunPee.
It tells you when the best times are to go pee during a movie so you don't miss a good part, plus a couple other nice features, like if the movie has an end credit scene. This is just a heads up, it's now free (temporarily?) for iOS. It is available for Android and WP, but is still .99 at time of posting.
I didn't try it because we rarely go to the theater to see movies, but for free, it's worth a look.