In the recording session scene for Judy Garland, the part of the conductor is played by the film's actual composer-conductor, Emmy winning Charles Fox.
It was reported in newspapers that Peggy Ann Garner was given the role of the studio teacher in this film and newspapers ran a photo of Garner taking McArdle on a tour of MGM but she is not to be seen. Garner's name was also included in some ads for the movie. There is no scene in the finished film that involved a studio teacher.
''Rainbow'' director: one-time child star Jackie Cooper, had played the love interest of Judy Garland in La danseuse des folies Ziegfeld (1941). As depicted in ''Rainbow'', Cooper and Garland - played by Johnny Doran and Andrea McArdle - had dated in 1936.
''Rainbow'' director Jackie Cooper hoped to film at the actual house in Silver Lake where the Gumm family had resided but was unable to come to terms with the 1978 homeowner. Therefore a house half a block down the street "stands in" for the Gumm residence.
Scenes set on the MGM lot were shot at Paramount Studios.