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.
At least three times, you will see trumpeters in the movie using mutes different from those on the sound track. 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" Doris.
Features one of the earliest references to homosexuality. The character of Amy played by Lauren Bacall is suppose to be a lesbian, which is why Rick, played by Kirk Douglas, walks out on her telling her that she is "a very sick girl".