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.
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.
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.
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.