Impossible physics: Why My Little Pony can't really fly

"Physical Impossibilities in My Little Pony: Friendship is Magic" is a student physics presentation that examines three scenes from an animated My Little Pony show (it looks like a recent adaptation, not the original) and identifies the physics at work, explains (with equations!) why the scenes don't work, and offers suggestions ("dark matter!") to fix them. The student has posted his slides as well. He says he got 100% on the presentation, and I believe it was a well-deserved grade.

Slides (PPT) (via JWZ)