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: When the helicopter lands and the teenagers cheer you can hear dialogue from later in the film in the background. Several times you hear "Sean, catch the rope." which they yell later in the movie.
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 David is in the steam bath talking on the phone, during the angle shot from behind, his voice is completely different as well as the background noise, much cleaner. It was very obviously dubbed. (00:39:40)