My Favorite Martian: Season 1, Episode 18
Martin and Tim are on their way to interview Professor Eugene Downey, the foremost expert on rocket fuel - Martin thinks the professor can assist in getting him back to Mars - when Martin is hit on the head with a monkey wrench. Martin gets amnesia from this concussion. He has no idea that he's a Martian, despite Tim telling him so. The only thing Martin and Tim can agree on is that Martin needs to go see a doctor. At Dr. Gilbert's office, Martin does learn that he has the power of levitation and the ability to disappear, still not quite believing why. The doctor, who witnesses the levitation, is told it's all magic. Back at the apartment, Tim almost has Martin convinced of his true identity when Martin is once again struck on the head, this time by a hammer. That's all he needed as he regains his memory. It's too late however: Professor Downey has already left town for good.