Other mistake: Once Dr. Trent enters the bedroom where Mrs. Loren is lying down "dead", they begin talking. Trent says "At first I couldn't get Nora to protect herself with a gun." There is no scene in the movie where he tries to convince her to use the gun, Lance is responsible for that. (01:02:25)DrLoomis1978
Other mistake: When Lance leaves Nora to go have a meeting with the remaining people in the house and they accuse Loren of murder, his room is locked from the inside but when he returns he opens the door without any trouble.