Not sure about directing, but I would definitely change some of the editing. Like that Stallone Lock Up movie I watched recently - it was supposed to be a gritty prison escape movie, but then there was this cheesy scene where I felt like I was suddenly watching The Westside Story. That scene totally took me out of the mood, I think it should have been left on the cutting room floor.Have we talked about movies and how we would change them if we directed them? I think that'd be an interesting idea.
That, and generally speaking, some movie scenes tend to be too long. It's like yes, we get the idea, no need to drag things out. (Unless it's an arthouse movie, of course, then such scenes are expected.) It's almost like when you have to write a college paper that requires a certain amount of pages, so you end up rambling endlessly in order to fulfill that requirement. I have little patience for that.