In an interview Esther Williams said that she met and spoke with Annette Kellerman before filming began, while attempting to get Kellerman's approval of Williams in the lead role. After the meeting Kellerman gave her complete approval and said she was pleased with the casting choice, though she good-naturedly complained that Williams was much prettier than her.
This film is considered the crown jewel of Esther Williams' career largely because, for once, MGM's writers were not called upon to find novel, far-fetched ways to get their star wet. Being the biography of a famous swimming star, the plot allowed Williams to organically spend nearly the entire running time in the water.
"Million Dollar Mermaid" became Esther Williams' nickname at MGM after the success of this film. It also became the title of her autobiography published in 1999.
A double was used for all three of Esther Williams' plunges in the mammoth Smoke number directed by Busby Berkeley. In the initial slide toward the water, the two women can be seen in the same shot, with Williams concealed beneath the water's surface as the double lands in the pool, ready to make her reappearance following the dive. Williams is clearly several yards closer to the camera, presumably to avoid an underwater collision.
According to contemporary stories in the Los Angeles Times and Australian newspapers, director Mervyn LeRoy met with Kellerman to discuss producing a sequel to this film that would cover her career in movies and her work with the Red Cross during WWII, but no such film was made.