Continuity mistake: In one scene, Elvis Presley's prison uniform displays the number 6239, yet in another it becomes 6240.
Visible crew/equipment: During the "How Long Has This Been Going On" number, Hepburn dances by a mirror - reflected in it are the camera crew, desperately trying to get out of the image.
Continuity mistake: When Fred Astaire and Cyd Charisse are dancing among the parallel bars, her skirt changes to cullottes then back again to an ordinary skirt.
Continuity mistake: When the three pigs are listening to the wolf playing his trumpet in Hell, the position of the double bass behind the pig who is playing the piano changes between shots.
Continuity mistake: The character Sid Sorokin sings the song "Hey There" into a dictograph machine. He then plays it back and sings a "duet" with himself. However, the lyrics and melody at the end of the song are different from what he sang into the machine originally.