- All-Star Cast
- Geoffrey Rush as Peter Sellers (and supposedly everyone else)
- Emily Watson as Anne Howe, his first wife
- Charlize Theron as Britt Ekland, his second wife
- John Lithgow as Blake Edwards, director/co-writer/producer of The Pink Panther (1963) and its sequels
- Stanley Tucci as Stanley Kubrick
- Miriam Margolyes as Peg Sellers, his Stage Mom
- Stephen Fry as psychic-to-the-stars Maurice Woodruff
- Edward Tudor-Pole and Steve Pemberton as Spike Milligan and Harry Secombe
- Billing Displacement: Charlize Theron doesn't get nearly as much screentime as, say, Emily Watson, but she's the biggest name besides Rush so she gets second billing.
- Deleted Role:
- Scenes were filmed with Emilia Fox as Lynne Frederick, but these were omitted from the final print. However, they are featured on the DVD.
- Rob Brydon played Dustin Hoffman in a deleted scene, which took place at the 1980 Academy Awards and involved Sellers losing the Oscar for Best Actor for Being There to Hoffman for Kramer vs. Kramer. During his acceptance speech Hoffman declared, "I refuse to believe that I beat Peter Sellers". Though the Academy Awards scene was deleted, the framing scene of Sellers watching it on television, is still in the movie. It has merely been re-edited, so what's playing on the television has been changed to the scene from Being There that he filmed. The look on Sellers' face as he watches, was originally his expression while rewinding the tape of Hoffman saying, "I beat Peter Sellers" and playing it over and over again. Stephen Hopkins says on the DVD Commentary, that the scene was altered because his dramatic point got lost in the exposition of showing Sellers' losing the Oscar.
- Fake Brit: Australian Geoffrey Rush as Peter Sellers.
- Fake Nationality: South-African-born Charlize Theron as the Swedish Britt Ekland.
- Screwed by the Lawyers: Sellers' final marriage to Lynne Frederick isn't mentioned at all, as the owners of Frederick's estate refused to let her be portrayed in the film. By that point, however, scenes highlighting it had been filmed (Emilia Fox plays Frederick) and appear as extras on the DVD release.
- Underage Casting: Geoffrey Rush was only one year younger than Peter Sellers was when he died, and here, plays him over the course of thirty years.
- What Could Have Been:
- The originally conceived Show Within a Show framework would have had Sellers' characters gathered together in the Dr. Strangelove War Room to discuss his life.
- Robin Williams was the original choice for Sellers, but he was too busy with other projects. Williams said it would have been a great honor to play Sellers, considering him his greatest influence as a comedian. Sacha Baron Cohen (who also credits Sellers as a primary influence), Steve Coogan and Kevin Spacey were considered at one point.
Trivia / The Life and Death of Peter Sellers