This was the only time, after becoming a star in the 1930s, that James Cagney accepted second billing for a major role. He thought that Doris Day's character was more central to the film's plot and so ceded top billing to her.
According to an interview with Ruth Etting, she never actually worked as a dance hall hostess. This was dramatic fiction, to underscore the song "Ten Cents a Dance."
Jane Russell turned down the opportunity to play Ruth Etting in hopes of landing the role of Lillian Roth in I'll Cry Tomorrow (1955). That role ended up going to Susan Hayward, leaving Russell with neither part.