Prior to filming, Lucie Arnaz (daughter of Lucille Ball and Desi Arnaz) had told writer/director Aaron Sorkin that it was okay to make Lucille stubborn and headstrong in the movie, as this was how she was in real life. After seeing the movie, Arnaz released a video on her YouTube Channel on 17 October 2021, in which she called the movie "freaking amazing." She complimented Sorkin for making a great movie that really captured the time period and had wonderful casting. She also said that Nicole Kidman "became my mother's soul." She also said that Javier Bardem didn't look like her dad but, "he has everything that dad had. He has his wit, his charms, his dimples, his musicality."
Desi misleadingly mentions that his family left Cuba due to the Bolshevik revolution, but in truth they left in 1933, two decades before the Castro revolution. There was a political coup in that year, but it was a different one.
Director Donald Glass is a fictitious person, either a composite of all the directors or representative of Marc Daniels, who directed "Fred and Ethel Fight."
Linda Lavin is the only actor in the film to have actually worked with Desi Arnaz, when he guest-starred on her series Alice (1976), which was also written by the character she is playing, Madalyn Pugh Davis. It was announced that Robert Pine was also cast in the film. He would have been the only actor to have worked with Lucille Ball, on her series The Lucy Show (1962). However, Pine is not in the final cut of the film, despite still being attached to it in online listings.
It was reported in January 2021 that Cate Blanchett had dropped out and been replaced by Nicole Kidman. Both actresses are Australian, and Blanchett provided a voice-over, at Kidman's suggestion, for her film De Olhos Bem Fechados (1999).