From 40 seconds to around 2:30 is the backwards shot.

A very good trailer we watched in class was the one for 'Memento'. I found the reversed filming very interesting, and a technique i would consider attempting to use. It still managed to build suspense even though you could see what had happened already and the events played out in reverse.
When the viewer sees the gun it becomes clear what has happened but very mysteriously we do not know why and it gives away very little about the film.