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.
Audio problem: While Bing Crosby sings "White Christmas," he is playing the piano. However, the piano is never heard.
Audio problem: There is a clear lip-sync problem in the boat scene, after Eugene takes out the lanterns.
Audio problem: In the last scene when Vlad, Michael and Ellen are swimming, Michael is talking as he enters the water. His head dips under water, but you can still hear his words.
Audio problem: When we see the moth singing on his way to the bar, his mouth doesn't move.
Audio problem: As the group approach Bluto's boat at Scab Island, Pappy is cranking a siren. A couple of seconds later, it sounds again, but he isn't touching it.
Audio problem: When Warren T. Rat calls open season on Fievel, the cats all scramble at once to capture him. In one shot where Fievel is running from either end of the piano, he jumps upon the same key twice. The notes play, but the key never goes down at all. (00:51:55)
Audio problem: When the wolves attack Maurice and Philippe, the wolves make growls that only big cats (lions/tigers) would make.
Audio problem: During "This is me", when they enter the room and get to the "oooh oh oh" part if you watch the albino the sync is out as their mouths open after the music has ended on that part.
Audio problem: After Chico and Harpo first meet there's a man at the opera playing a drum. Not only is he out of sync with the sound we hear, but he is mimicking the blows.