Buster Keaton was working as a gag writer at MGM when this movie was made. The filmmakers approached him to devise a way for a violin to get broken that would be both comic and plausible. Keaton came up with an appropriate fall, and the filmmakers then realized he was the only one who would be able to execute it properly, so they cast him in the film. Keaton also devised the sequence in which Van Johnson inadvertently wrecks Judy Garland's hat, and coached Johnson intensively in how to perform the scene. This was the first MGM film Keaton appeared in since being fired from the studio in 1933.
Liza Minnelli appears in the final scene. She's the "Babe in Arms" held by Andrew Delby Larkin (Van Johnson) and Veronica Fisher (Judy Garland), as the credits start to roll "The End; Made in Hollywood, U.S.A. by Metro-Goldwyn-Mayer". It was Liza's film debut.
Charles Smith, who plays a member of the barbershop quartet, also played the role of Rudy in the The Shop Around the Corner (1940), an earlier version of this movie's storyline.
Marcia Van Dyke, who plays Louise Parkson, was an accomplished violinist and did all her own playing in the film.
The street of Victorian era houses on which Van Johnson and Buster Keaton go bike riding originally was built as "Kensington Avenue", where Judy Garland and her family lived in Meet Me in St. Louis (1944).