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 Stone. After a few months, Larson dropped out. After Stone's schedule was cleared, she was able to take back the role.
The film sugarcoats the tragic love affair with Marilyn. What was private until 1981 became public when Marilyn sued King by invoking the palimony law nearly destroying King's career. It would take years from then for King to rebuild what she'd lost.
Whilst riding in the car, Billie Jean King and Marilyn listen to an Elton John song. By 1974, John had become friends with King, and co-wrote his hit single 'Philadelphia Freedom' as a favour to her.
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).
Jonathan Dayton and Valerie Faris previously directed Steve Carell in Little Miss Sunshine (2006).
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.
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).
Bobby Riggs' training partner and friend Lornie Kuhle is played by Eric Olsen in the movie. The real Lornie Kuhle makes a cameo in the movie playing Pat Summerall, the newscaster seen at the beginning of the match between Bobby Riggs and Margaret Court.
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.