In her essay "Humphrey and Bogey", Louise Brooks wrote that more than any other role that Humphrey Bogart played, it was the role of Dixon Steele in this movie that came closest to the real Bogart she knew.
The pianist and singer in the film is Hadda Brooks. While she originally came to prominence with boogie woogie, she was best known for ballads and, unusual for singers of her day, she wrote many of her own songs. She continued to perform into the 1990s.
Producer Robert Lord was worried about having Nicholas Ray and Gloria Grahame, then husband and wife whose marriage was on the rocks, working together. He made Grahame sign a contract stipulating that "my husband shall be entitled to direct, control, advise, instruct, and even command my actions during the hours from 9 a.m. to 6 p.m., every day except Sunday. I acknowledge that in every conceivable situation his will and judgment shall be considered superior to mine, and shall prevail." Grahame was also forbidden to "nag, cajole, tease, or in any other feminine fashion seek to distract or influence him."
Gloria Grahame and husband and Director Nicholas Ray quietly separated during filming, keeping it a secret for fear that one of them would be replaced. Ray slept on the studio set, saying that he needed to work late on preparation for the remainder of the film. It worked, and nobody suspected that their marriage was on the rocks.
The apartment complex in which Dixon (Humphrey Bogart) and Laurel (Gloria Grahame) live was a replica of Nicholas Ray's own residence when he first moved to Hollywood.