And a near perfect example of the 'unexpected but inevitable event that set our protagonists off in a different direction' that should, according to the Hollywood formula, occur at the 15 minute mark. The only time I watched Creature I had the On Screen Display of my DVD player running because I was researching the 15 minute rule in crap films. In Creature the ground beneath a safely landed spaceship collapses - thus changing a rescue mission into a survival mission - bang on 15 minutes elapsed running time.
Thinking about it, my greatest Guilty Pleasure Movie has to be Starcrash - which just has everything you could wish for in a movie.
Starcrash is a good bad film. The acting and writing, directing is atrocious and the special effects look like every 60's B film I've ever seen. But is it a very entertaining and fun film to watch.