One common mistake we often see in pitches -- too much information is put on slides. This can create a couple of problems: First, cramming information to get all the points across invariably means the font size is small and we cannot read it. But since you put it there we will try and then become distracted from what you are saying, thus losing track of your presentation. Second, if the information is not complete or it's complex it sets us thinking or struggling to figure something out. Again, we're not listening to you.
Bottom line: keep the slides very simple (animation is OK for something complex but be sure its done well and each step itself is easy to follow and understand).
Investors want to see you in action and listen to you hit the highlights of your business. Don't make us think, or read for more than about 5 seconds, on each slide.