When Cody is making the sets for the theater, he ''hits'' his thumb. But if you look closely you can see that he tucks his thumb into his hand and he hits the wood a good three inches away from his thumb.
Even though Frank's wedding ring is missing, it seems obvious that Patrick Duffy is wearing his wedding ring.
Each time Dana is told to scream, you can hear the producers (or someone) scream first to show her how to scream each time.