Corrected entry: You can see Sam's shadow the whole time.
Corrected entry: At the end, after Sam moves the penny to convince Molly that Oda Mae is telling the truth, they all go into the apartment. Now, knowing that a murderer, Carl, is on his way to come and get them, you would think they would all get out of there as soon as possible. Instead, they wait around until Carl shows up, and then act all surprised and run when he gets there.
Corrected entry: In one of the last scenes, Oda Mae, Sam and Molly are at Molly's house, waiting for the police. By now Sam has learned to touch things and people. But he does not seem to be able to touch Molly and needs to borrow the body of Oda Mae to touch Molly and dance with her.
Corrected entry: Willy gets inside Molly's apartment very quickly after Carl gets her to go out and take a walk with him. He's unable to get what he came for, and then goes straight to his house, where he contacts somebody on the phone - it can only be Carl. His explanation for why he couldn't get it? "She came home." But since it can only be Carl he was talking to (this is made clear by Carl's visiting Willy later on) Carl knew perfectly well that Molly came home. It's Carl that Molly was with - he'd have known full well that she left his company.