Audio problem: When auditing the recording of one of the first hijacks, the FAA reviewer rotates the tape reels back and forth in order to find just the exact words from the hijacker. As the sounds play, the reel moves barely half a turn, but the reviewer rewinds it more than one revolution, not nearly returning to where that sound would be.
Audio problem: When Rene Gagnon is playing the guitar on the ship his hand movements do not match the guitar that is playing.
Audio problem: In the very final scene where the Scottish pipe band is playing the tune "Amazing Grace", it is apparent that the music is overdubbed and professional musicians were not used for the visuals. When the pipers are slow-marching, the marching is shoddy with different people stepping at different times ("experts" would be very precise). As the camera pulls back past the drummers, it is clear that some of them are beating their drums at a very different time to the sound track.