During the performance of "Mister Yankee Doodle," a band of some sort flies off Rosario's costume and lands on the floor. It remains there for the remainder of the number, even getting stepped on and breaking; it is likely that there was no time for another take. It only disappears after the number's conclusion, when the couple takes a bow in a long shot.
The song The Boogie Woogie Boogie Man, was used again in Universal's 1944 musical/murder mystery MURDER IN THE BLUE ROOM.
In addition to MURDER IN THE BLUE ROOM, "The Boogie Woogie Boogie Man" also appeared - sung by the Brian Sisters - in RHYTHM REVEL, a 1941 Universal two-reeler.
The shot of Mischa Auer sitting in a chair holding his cane and gloves while he watches rehearsal was used by Universal to announce Auer in the cast of HOLD THAT GHOST in that picture's theatrical trailer.