The film, adapted from a biography by Roger Lewis of the same title, chronicles Sellers' life and career from The '50s and his breakout success on The Goon Show up through the production and release of his pet project Being There at the turn of The '80s (his death came soon after that). However, it focuses mostly on The '60s: He lets an obsession with Sophia Loren destroy his first marriage, finds international critical and commercial success with his collaborations with Stanley Kubrick and Blake Edwards but not without on-set turmoil, experiences an octuple heart attack shortly after marrying starlet Britt Ekland, and proceeds to let that marriage disintegrate as well.
This film is also a tricky example of Postmodernism. It is actually presented as a Show Within a Show that Sellers himself (as played by Geoffrey Rush) is directing and playing all the roles in. Most of the time, the other people "appear" to be played by an All-Star Cast, but from time to time the framework is returned to and said person is revealed to "actually" be played by Sellers...who, remaining in character, lets the viewer in on "their" opinion of him. The viewer is left to wonder if he's trying to draw us into the truth, distance us from it, or both.
This was the first produced screenplay for writers Christopher Markus and Stephen McFeely, who have since co-written The Chronicles of Narnia film adaptations and several entries in the Marvel Cinematic Universe (the Captain America films and Thor: The Dark World, to be specific).
This film contains examples of:
- Anger Montage: Intercut with the Costume-Test Montage, Peter destroys most of his old home movies and film memorabilia near the end of the film.
- Animated Credits Opening: As per many of Sellers' actual films, the first stretch of the opening credits is one of these, set to "What's New Pussycat?" and featuring loads and loads of animated Peter Sellers gadding about. Also an example of...
- Bait-and-Switch Credits: It's light and funny to deliberately contrast with the mostly-miserable story of a mostly-miserable person that follows.
- Byronic Hero: The portrayal of Peter Sellers in this film is firmly in passionate-but-troubled-and-troubling territory, ultimately presenting him as a Villain Protagonist in his own life.
- The Cameo: Heidi Klum as Ursula Andress in the Casino Royale sequence.
- Costume-Test Montage: As Peter prepares to shoot Being There; also a Writer's Block Montage of sorts as he's alone in his Swiss home at the time, isn't happy with any of them, and it reflects his larger problem of how to approach the character of Chance.
- Domestic Abuse: After Peg dies, Peter and Britt wind up in a physical fight that he starts. Even before that, he's tough on his first wife and children, i.e. smashing up his son Michael's toy cars after he accidentally ruins a new sports car with touch-up paint.
- Downer Ending: Peter gets his dream project made and it is a huge success, but he's alienated so many people close to him that he's virtually alone in the world and dies less than a year after the film's release. The text epilogue notes that his children didn't get much in his will, and that the only thing found in his wallet when he died was a picture of his first wife.
- Executive Meddling: In-universe in a Deleted Scene that appears on the DVD: the film's producer and director argue about whether Peter can be made sympathetic and whether they need to go into detail on his third marriage and/or his career downturn in The '70s. The answer to all three turns out to be no. Keep in mind that they're both being played by (Rush-as-)Sellers.
- Falling-in-Love Montage: For Peter and Britt.
- Happier Home Movie: Near the end, Peter is alone in Switzerland watching home movies of him with his fellow Goons and his first wife and their children, and is so absorbed in this that he lets a phone call from his now-adult son go to the answering machine.
- Historical Villain Upgrade: Both Peter Sellers and his mother get this, hitting a low point with the latter by having her hide the fact that his father is dying from him so that he only gets to see him briefly before he expires. In real life, Sellers was quite aware of the illness and was not with him when he actually died — he was at a Judy Garland concert, and regretted going when he found out what happened.
- Just Here for Godzilla: In-universe. At the premiere of The Pink Panther Strikes Again, Peter claims to the crowd that people only go to see the Pink Panther films to watch him, as their director/producer/writer is a hack. (This incident is completely fictional.)
- Loads and Loads of Roles: Geoffrey Rush plays Peter Sellers, Sellers' characters, and in the movie's framework, other people in his life. Basically, he's apparently playing everybody.
- Lonely at the Top: Peter, at the end.
- Madness Montage: After Britt leaves him, Peter has a (partially animated) one that doubles as a Time-Compression Montage for the next several years, as he falls into substance abuse and his career goes into decline.
- Manchild: Deconstructed with Peter — due to his mother indulging him all of his life and encouraging him to look out for number one, he's grown up to be incredibly selfish and demanding, and prone to throwing violent tantrums.
- Phony Psychic: Stephen Fry shows up as one of these; the first thing he tells Peter Sellers is nobody should wear green because it's bad luck. Later we see him on the phone wearing the exact same green sweater he advised Peter Sellers not to wear.
- Playing Sick: Peter doesn't want to play his planned fourth role (Major Kong) in Dr. Strangelove, and his son suggests he do this to get out of it. Peter proceeds to arrive on set in a leg cast, walking on crutches... (In truth, he got out of the role by playing up an actual ankle injury he sustained on the set when he fell out of the prop cockpit.)
- Take Our Word for It: Audiences in-story react with glee to Sellers' film performances, but the viewer usually doesn't get to see exactly why. There are quick clips of Rush-as-Sellers in films like I'm All Right, Jack and The Mouse That Roared, but he isn't doing anything particularly funny in them. The filmmakers apparently assumed the viewer was familiar with Sellers' work going in and would be able to fill in the blanks.
- Time-Compression Montage: One charts his rise to U.K. film stardom (and has the Take Our Word for It clips mentioned above) and his family moving from an apartment to a mansion.
- Unreliable Narrator: The movie often switches to many of the other people in Sellers' life as being played by Sellers himself, where they will offer commentary on Sellers as they saw him. It is left to the viewer to determine whether these are accurate depictions of what they thought about Sellers or simply what Sellers believed / wanted them to think about him.
- Villain Protagonist: Peter Sellers ends up coming off as this between the Byronic Hero portrayal, the Historical Villain Upgrade exaggerating some of his worse tendencies, and the fact that the healthier relationships he had in his life (in particular with his fellow Goons) are neglected/downplayed. Arguably justified in that he was a domestic abuser among other things, so a portrayal that put more/equal emphasis on his positive aspects would have run the risk of downplaying the damage he did to himself and especially others, and as Society Marches On it is much less forgiving of such portrayals of real-life figures.