Judy Garland was scheduled only to sing with Mickey Rooney in this film, and producer Arthur Freed offered her $50,000 (or half of what she owed the studio for medical bills) to do one take. At the first public screening, the fans asked for more of her, so Freed offered her another $50,000 to do a second song. By the time her scenes were filmed, she had paid back the studio but had made nothing.
Eddie Lorrison Anders:
Hi ya, Mom!
Mrs. Hart: Hello, Eddie.
Eddie Lorrison Anders: Have you seen the notices? Oh, they're terrific. Mom, we're a smash!
Mrs. Hart: Well, certainly.
When Judy is singing "Johnny One Note," and gets to the line "... and hear the drum," it is obvious that the snare drummer is not playing what we are hearing.