Revealing mistake: When the first scene at Emma's hideaway was shown, obviously the two characters Emma and Jessica were filmed seperately on the couch and then the film was put together (as both are played by Angela Lansbury). However Jessica did a lot of moving while she was talking, so Emma was looking straight across at where she had been, despite her bending down while she talked.
Audio problem: When singing "Goodbye little yellow bird" Emma blows a kiss to Oliver offstage, but she is still singing the song when she is blowing the kiss. Although it's possible she was pretending as it was part of the act, her voice wasn't even muffled by her hand.
Continuity mistake: When Emma was almost hit by a car she jumped up onto the edge of the wall and then back down onto the floor. When she landed she was facing the theatre door, but when Oliver came of the door and the shot changed, she was facing away from the wall. This happened in the transition from stunt person to Angela.
Revealing mistake: Kat pumps her shotgun several times with no shells coming out.
Plot hole: When Beverly is killed the killer shuts off the main power switch which would have turned all the lights off in the house, not just those in the bathroom. (01:31:00)
One Good Bid Deserves a Murder - S2-E17
Continuity mistake: The first time Jessica is shown asking for her room number, she asks for room 812. Later in the episode she asks for room 810.