Continuity mistake: The kid holding Eraserhead's head is wearing glasses, yet he had not been wearing glasses prior to that. He is only wearing glasses when he is not facing the camera, but the camera is just to his right so you can see the right frame and lense. Once he turns to go into the pencil room to have the brain examined, he is no longer wearing the glasses. (01:09:35)
Continuity mistake: Henry takes off the wrong shoe/sock to dry off.