Crew or equipment visible: After the car chase when Fred catches Ginger, the sound of someone coughing can be heard.
Revealing mistakes: During the "Continental" sequence Rodolfo Tonetti is shown playing a concertina and singing along. Though he moves the concertina in and out, and you can hear the music, his fingers never move on the keys.
Continuity: When Hortense first meets Tonetti, she is wearing a black cape. When she goes back upstairs to warn Mimi that she might have the wrong man in her room, she doesn't have the cape on. Then when she returns downstairs and talks to Egbert, she's wearing the cape again.
Continuity: When Tonetti and Guy are tied together after the night in the hotel room, they make a number of moves where they try to go in opposite directions, but are unable to because they are tied together. When the doorbell rings a final time Tonetti goes to answer the door and Guy goes to comfort Mimi, they are no longer tied together.