Audio problem: In the contest, there is a little boy playing "When the Saints Go Marching In" on a trumpet. While this is going on, Michelle and her friends are shown backstage getting ready to go on next (you can still see the boy playing in the background). In this shot, the boy's finger movements on the trumpet do not match with the music we hear.
Audio problem: When Jesse is telling Michelle that it is time for him to start acting like a mature adult, he then proceeds to call out for Joey. However, in the scene, you can hear an audio of Jesse's voice faintly calling out "Joooeeeeeey!" without any lip movement immediately prior to Jesse actually calling out Joey's name. (00:23:25)