Visible crew/equipment: When Groucho enters the rehearsal area, the shadow of the camera is visible behind him.
Continuity mistake: Curly's shirt is stained with clay, yet he hasn't been hit in the chest yet.
Continuity mistake: When Minnie Mouse falls down on the pillow whilst attempting to skate, the pillow bursts and covers Mickey with feathers. When Mickey goes off skating you can see nothing surrounding the pillow, but when we return to Minnie later on, there are now a lot of feathers around it.
Continuity mistake: When Donald Duck is holding on to Mickey Mouse when Goofy is dangling on the ladder, you can see there is a window underneath Donald, but when he has his feathers burned in the next shot, the window has disappeared.
Continuity mistake: During Astaire's big number "Top Hat, White Tie and Tails," he produces an invitation on stage, sings about it, then crumples it up, and tosses it away. It must be nearby on the stage, but when we finally see the entire stage, the invitation is gone.
Continuity mistake: When Mickey Mouse is preparing to start the concert, you can see that he has a music book on the stand in front of him. When the band start playing in the next shot, the book has disappeared, and in the shot after that, it is back again.