Carrie Fisher said she was cast in the role mainly through family connections. She said when Warren Beatty ran lines with her, he did it while eating. She said the whole thing for her was a lark. She also admitted years later in an article she wrote for Rolling Stone magazine that star Beatty unsuccessfully propositioned her.
Loosely based on "The Country Wife," a Restoration comedy written in 1675 by William Wycherley, whose protagonist Horner feigns impotence in order to be allowed into the company of married women, who he then seduces. George in "Shampoo" would be considered non-threatening due to the stereotype that hair-dressers are gay, such as the scene in Jackie's bathroom when Lester walks in and the bistro sequence when George is fluffing Lester's hair. "Shampoo" only retains a distant reflection of the Horner character, but reportedly, the screenplay was inspired by the 1969 Chichester Festival production, according to a 2003 edition of the play edited by James Ogden.
Lee Grant claimed in her 2014 autobiography that "everyone knew" Goldie Hawn and Warren Beatty were sleeping together, even though he was still involved with Julie Christie. On the contrary, Goldie had earlier told biographer Suzanne Finstad in 2005: "I didn't become one of Warren's 'girls,' and I'm very happy about that." However, her account was also contracted by ex-husband Bill Hudson, who claimed in his own 2011 memoir that the two did indeed have an affair, though not necessarily during the filming of this movie. According to Hudson, Hawn confided to him that a liaison with Beatty occurred when they co-starred in $ (1971), under the nose of her first husband Gus Trikonis who was making a behind-the-scenes documentary about the film.
Perhaps to give audiences impression the film was au courant, the movie's poster featured pictures of three leads (Beatty, Christie and Hawn) as they appeared in 1975, not as characters with dated hairstyles they sport in film set in 1968.
Warren Beatty rides a 500cc Triumph Tiger 100 motorcycle, registration 356455. The paint job is not standard despite the incorporation of the Triumph logo and it is uncertain whether it was Beatty's personal bike.