In 1969, while still a member of the Mamas and the Papas, Phillips acted in Gram Parsons's science fiction film "Saturation 70" alongside Nudie Cohn, Anita Pallenberg and Julian Jones, the five-year-old son of Rolling Stones guitarist Brian Jones. The film was never finished, and became a lost film. The following year, after the breakup of the Mamas and the Papas, she enrolled in acting classes in Los Angeles and has said that she had intended to start her acting career "from scratch", stating that the royalties from the band's records provided her a sustained income while she began to venture into film. She studied acting with Peggy Feury.