Visible crew/equipment: In the scene where the knights are attacked by the killer rabbit outside the cave, you can see the boom mic at the top of the frame.
Revealing mistake: When the stripper appears from the changing room during the cabaret scene, the stripper music is heard, but if you look carefully the tape recorder which is supposed to be playing the music is not actually moving.
Revealing mistake: Near the end of the movie in the shot when Giorgio Perozzi is dead on his bed you can see him breathing twice.
Audio problem: In the "How Lucky Can You Get?" musical number, when Fanny is turning on the stage lights she is not singing, although Streisand's singing voice is heard on the soundtrack.
Factual error: When the Chinese are loading crates onto the truck with St Paul's in the background, two much more modern buildings are visible either side of the cathedral - out of keeping with the 1910s/20s setting.
Audio problem: When Kipper are performing towards the end of the film, Tim the drummer is late on stage and the other band members have started to play their instruments, but you can still hear the drums play before Tim picks up the sticks.