Revealing mistake: In the swimming pool scene, when David is sitting at the bottom of the pool, you can clearly see a scab on one of his knees. (00:43:00)
Revealing mistake: When the robots start to scavange the pile of robot rubble the moon balloon comes over. One of the robots shouts, " Moon on the rise!". If you look carefully you can actually see the actors' real bottom lip behind a metal robot jaw that isn't meant to have any flesh or skin. (00:58:15)
Revealing mistake: When Monica is reading to Martin, her cryogenically frozen son, you can see the body move. (00:08:00)
Chosen answer: His license is a tracking device. By removing it, he's preventing the authorities from easily tracking him.