Actually, JoshGage, the magnet is set to repel. So when the obstacle (i.e., the door) is removed, the metal block is repelled right out the doorway. It's not magic... it's SCIENCE.
Arcade mode has a bug - once you completely power up the ship, the exp coins don't get collected. Which shouldn't be a big deal, but as they amass more and more, the game slows to a crawl trying to keep track of them. Also, the upgrades selected in arcade mode aren't that great and make beating the 2nd to last boss (I think) extremely difficult.