Also, just because the mtt says a prof is teaching a course, doesn't mean he/she actually is. For one of my courses last year, it said that we were going to have the prof that taught the course the year before, even though that was never the plan. They had another guy who was going to teach the course, but then that fell through last minute so we ended up with some random.
Profs also sometimes switch sections--I remember my friend really wanted to get into a specific prof's section for chem 1AA3, and then finally a spot opened up and she got in, only to find out that the prof had switched to teaching a different section of the same course.
Basically, nothing is set in stone until you go to the first class