After initial previews, much of the film's ending was re-shot in order to make Gene Kelly's draft-dodging character Harry Palmer more sympathetic to wartime audiences. The scenes in which Palmer becomes a hero in combat were among those added.
Producer David O. Selznick had brought Gene Kelly to Hollywood from New York but couldn't find a suitable vehicle for him, so he allowed Kelly to sign a contract with MGM, where his career flourished beginning with this film.
Mártha Eggerth's solo number, "The Spell of the Waltz", was cut before the film's release. The footage of the number does not survive, but the audio does and was included on the Rhino Records soundtrack album along with several other cut songs featuring the film's principal cast.
Richard Quine, who plays Judy Garland's off-to-the-war brother, later moved behind the camera and directed such films as "The Solid Gold Cadillac," "Bell Book and Candle," "The World of Suzie Wong," "Sex and the Single Girl," "How to Murder Your Wife," etc.
Judy Garland got Gene Kelly for this film when MGM didn't want him. He repaid her the favor with summer stock. Judy Garland was at the end of her contract with MGM and Gene Kelly insisted she be in the film with him.
The trivia item below may give away important plot points.
Jo's brother, Danny, was killed in action on September 28, 1917. Later in the movie, Jimmy Metcalf "paid" a French taxi driver with a men's clothing store coupon for a sale that ended on June 15, 1914, over 3 years earlier.