I wasn't even aware that this was an issue, but apparently it is. From Amazon's page for Hasbro's Thor Lightning Hammer:
• Carry the hammer of Thor, the Mighty Avenger! Modeled after the hero's weapon in the Thor movie. With thunder sounds, flashing lights, and launching missile. Keep Loki out of your room!
• Inspired by the Thor movie, this amazing Thor Electronic Hammer will give you the powers of Thor! (Or a reasonable plastic facsimile thereof.)
• Featuring a launching missile, as well as electronic lights and sounds, this nifty mock weapon is the best way to keep Loki out of your room.