Continuity mistake: As the New Main Street Singers are performing their second song at the show, you can see Parker Posey pretend to use her guitar as a shotgun. The strap for the guitar drops from her shoulder down to her right forearm when she does this. When the shot changes the strap is back up over her shoulder.
Continuity mistake: When Jonathan Steinbloom is introducing Mitch and Mickey at the concert, he has the blue paper in his right hand and it's lifted up to around his chest. However, when we see a shot of him from behind, both hands are by his sides. Immediately when the shot changes to show him from the front, his hand is at his chest again.