Other mistake: As the police lift the body of the 'dead' hotel clerk from behind the desk, you can see his eyes look around a bit.
Continuity mistake: Marsha Mason is standing between Abe Vigoda and Vic Tayback.After a quick close-up of Peter Falk suddenly she is standing next to Peter.
Continuity mistake: When "Ms. Montenegro" is talking to Lou about her niece at the Convent and Kennels, he sits down, and next to his elbow there's an object on the desk. After a quick cut, the object has disappeared entirely with no explanation and with Peter Falk in the same position as before. (00:12:00)
Revealing mistake: Lou received Georgia's rather incriminating phone call. Only his bedside lamp is lit, supposedly, but when he opens the drawer of the nightstand the lamp is on, it casts a light on the wall above, revealing the presence of more sources of lights in the room. (00:07:00)
Continuity mistake: Lou hands a dry martini with onion to Madeline Kahn's femme fatale. She takes the glass with the right hand and begins stirring the drink with her left hand. New shot, and she is holding the glass in her left, stirring with her right. (00:09:50)
Continuity mistake: During the first meeting between Lou and Madeline Kahn, her fur stole changes position between shots almost more often than she changes names. (00:09:30 - 00:10:30)
Continuity mistake: When the police officer enters the hotel room with the elderly couple, the old man has his mouth open wider in the second shot, and the woman is looking straight ahead instead of up. (00:05:45)
Factual error: The credits roll closes with the caption "San Francisco...seven thousand miles away from Casablanca." San Francisco is less than 6,000 miles away from Casablanca. (00:03:20)