The film contains a reference to homosexuality, although the Hays Office--the industry's censor--required any mention of it be subtle. The character of Amy (Lauren Bacall) is lesbian, which is why Rick (Kirk Douglas) walks out on her, telling her that she is "a very sick girl". Many decades later, Bacall told a Turner Classic Movies interviewer that the reference was so subtle (and she was then so young and naive) that she didn't understand until years later that the character she played was supposed to be lesbian.
Doris Day wrote that she was unhappy making this film, which brought back stressful memories of her early career as a band singer, and also because Kirk Douglas and Lauren Bacall (having dated at one time in real life) seemed to intentionally shut her out, making her feel unwelcome.
The three main actors all proved to be remarkably long-lived. All were around to celebrate the 64th anniversary of the movie's release. Lauren Bacall passed away in 2014 at the age of 89, but as of April, 2018, Kirk Douglas and Doris Day are still alive.
At least three times you can see trumpeters using mutes different from those on the soundtrack. For example, in the Christmas Eve scene Rick is shown using a Harmon mute and Harry James' dub of the tune is with a cup mute.
Even while married to pinup-girl Betty Grable, Harry James was notorious for his womanizing. Peter Levinson, in his biography of James ("Trumpet Blues") notes that during the filming of this movie, James contacted Doris Day's manager to ask what he thought were James' chances of "nailing" Day.
Although this was only her fourth film, Doris Day's screen persona as "The Good Girl Next Door" was already established. Here, Day plays a decidedly secondary role, that of the woman who tries to encourage and redeem the Kirk Douglas character, while Lauren Bacall portrays the woman who essentially lures him to his ruin.
Hoagy Carmichael was a friend of the real-life Beiderbecke and helped Douglas with his role. Carmichael received a thank-you letter from director Michael Curtiz for his valuable input in several areas of this film's production.
The trivia item below may give away important plot points.
This film's odd, upbeat ending, in stark contrast to the agonizing early death of Bix Biederbeck, was solely due to the will of studio boss Jack L. Warner. Kirk Douglas and Michael Curtiz lobbied for a more downbeat - and true-to-life ending.