Hidden Mickey's are everywhere at Disney! It's fun to try and spot them on the walls, the floor, in pictures...they are everywhere. My 2 kids like to keep the Disney Magic going even while we aren't on vacation by pointing out things to me like: "Look! Those chocolate chips are a hidden Mickey!" "Hey! Those spots on the sidewalk are a hidden Mickey!"
There are some books out there to show you where some of them are, and of course, it's just fun to discover on your own!