Audio problem: Although Kevin Spacey actually sang for the soundtrack, his lip-sync blunders are noticeable in every song, and virtually all of the musical routines in this film are out-of-sync with the audio track. Even rhythmic hand-clapping on stage is out-of-sync.
Audio problem: In the very first scene of the movie when Bobby is recreating his performance at the Coconut Grove, the actions of the band are out of sync with the music we hear. (Bobby is in sync, but the band is not.) Watch the hands of the drummer and the band leader: The entire scene is out of sync, but when the drummer moves to the ride cymbal you can easily see he is ahead of the music, and when the band leader gives the band cues for accents, his hand movements are behind the music and therefore happen too late.