Wired:

Thor’s hammer Mjölnir would be the most badass weapon in comicdom even if its name didn’t sound like a Norwegian black metal band. But Marvel would have us believe that the hammer is also the god of thunder’s primary mode of transportation, and that is an unforgivable crime against the laws of physics. So we’re supposed to believe that he spins it, hurls it, and then hitches a ride on it? It’s like these people have never heard of the law of conservation of momentum!

By all means, watch the video but, and I’ve never said this before, make sure you read the comments section for the absolute nerd-gasm that is going on.