In 1973, Billie Jean King was 29 and Bobby Riggs was 55. At the time of filming, Emma Stone was 28 and Steve Carell was 54.
Emma Stone was initially cast as Billie Jean King, but scheduling issues forced her to pass on the role. Brie Larson was ultimately tapped to replace her. After a few months, Larson dropped out. After Stone's schedule was cleared, she was able to take back the role.
Whilst riding in the car, Billie Jean King and Marilyn Barnett listen to an Elton John song. John and King were friends by 1974, and they co-wrote his hit single 'Philadelphia Freedom' as a favor to her.
The film sugarcoats Billie Jean King's love affair with Marilyn Barnett. In 1981, Barnett sued King, invoking the palimony law, and nearly destroying King's career. It took years for King to rebuild what she'd lost.
This is the first time Danny Boyle has produced but not directed a film since 28 Weeks Later (2007). Boyle was originally set to direct, but had to leave due to scheduling conflicts with Steve Jobs (2015) and T2 Trainspotting (2017).
Vince Spadea and Kaitlyn Christian served as tennis doubles for Steve Carell and Emma Stone. Christian had a five-week contract, but filming ultimately took around four months.
Bobby Riggs's hustling and male chauvinism were known prior to his match with Billie Jean King, but became more infamous afterward. In 1973, he guest starred as himself on an episode of The Odd Couple: The Pig Who Came to Dinner (1973), in which he hustled Oscar Madison out of everything, including his apartment lease and Felix. Riggs also gambled with Felix, betting that he would become a member of the male chauvinist club, Riggs' Pigs, if Felix lost. Billie Jean King also appeared in the episode.
Jonathan Dayton and Valerie Faris previously directed Steve Carell in Little Miss Sunshine (2006).
Five of the supporting cast members are sketch comedy veterans. Steve Carell was a writer and cast member of The Dana Carvey Show (1996). Sarah Silverman and Tom Kenny were cast members of Mr. Show with Bob and David (1995). Fred Armisen was a cast member of Saturday Night Live (1975) and a cast member/writer/producer of Portlandia (2011). Chris Parnell was a cast member of Saturday Night Live (1975).
Fred Armisen played Billie Jean King on Saturday Night Live (1975), in a sketch with Andy Roddick.
Steve Carell and Wallace Langham previously appeared in Little Miss Sunshine (2006).
Reunites Elisabeth Shue with Wallace Langham after CSI: Crime Scene Investigation (2000). However, they don't share any scenes.