Audio problem: During "We Go Together" at the end, John Travolta's mouth is not in sync with the words "we'll always be like one." He appears to start singing "that's the way it should be" before realizing and correcting his mistake.
Audio problem: In the plane, when the Captain says "I'm not too god, what do you think" his lips aren't moving.
Audio problem: At the bar after the tall black man asks to dance with the boys' dates, he lifts the booth table up off the floor. There's a sound like it's being forcibly ripped out of the floor, yet the table has a round bottom with no visible bolts or screws. While it may have been heavy, it wasn't secured to the floor.
Audio problem: Near the end of the film, when the Commodores finally go on stage with their equipment, Bobby Speed announces them from inside the control booth. But the movement of his mouth does not match the audio (you have to look at his reflection in the glass wall).
Audio problem: Right after Hooper says "Bye bye, nice officer." and activates the rocket system, the cop driving beside them screams "Great God almighty.". Watch the cop's rear view mirror when he yells that - it's a completely different person in the mirror and his mouth doesn't move at all, much less yell "Great God almighty." But when he calls "Headquarters. never mind", on the radio, the original cop is shown again.
Audio problem: When Cheech and Chong are being questioned by the officer at the border, the officer says "you got any narcotics, any marijuana in here?". His lips continue moving but we can't hear him. (00:45:45)
Audio problem: The scene in Dudley Moore's apartment was longer than the song, "Stayin' Alive" that is playing on his stereo so the song is substantially longer by looping and replaying portions of the song. (00:30:20 - 00:36:00)