2) Thinking It's Only the Magic Kingdom
One misconception that is way too common is that Walt Disney World and the Magic Kingdom are the same thing, or that the Magic Kingdom is the only theme park. True fans know that it's so much more than that. Walt Disney World has four theme parks, not just the Magic Kingdom, two water parks, a shopping and entertainment district, and so much more. It's possible to spend an entire week at Walt Disney World and never enter the Magic Kingdom, and still have a great time. You could do that, but why would you want to?