There's a scene in the trailer (available on the DVD) where Sleven can be seen walking away from an explosion in the movie. In the movie, the scene's there, too, but Sleven's not exactly alone. They edited out the other individual for the trailer (or vice versa)! I, as a movie goer, really appreciate being thought of like that.
And for those of you who don't want to be spoiled but are wondering why I'm making a big deal of it: There's a clip in the trailer that was edited with a post effect just to not spoil the viewer.
That's deeply considerate for the editors to care enough about our movie experience to not ruin it with a too-revealing trailer!