When the Gallos revolted against their boss, Joe Profaci, they went to war and rented apartments stocked with mattresses. An associate of the Gallos was killed while on a fishing trip with friends, and the Gallos were sent a fish wrapped in a box just as when Sonny gets Luca Brasi's bulletproof vest with a fish. Also, terms like 'Sleeping with the fishes' and 'Hitting the mattresses' came from the lives of the Gallos. In the movie, Sonny is the 'hot head' (Like Crazy Joe), Michael is the thoughtful and intelligent one (Like Larry Gallo), and Fredo is the dimwit (Like Michael Gallo). Specifically, he borrowed a lot of from the life of New York City gangster 'Crazy' Joe Gallo, including the dynamics of he and his brothers. When writing the novel, Mario Puzo either directly or indirectly borrowed ideas from real-life Mafia stories. Actor Gary Kurtz was in the Marine Corps during the Vietnam War and Ron Gilbert was drafted into the Army in the summer of 1960.

Other cast and crew members served in the Korean War including cinematographer Gordon Willis who was in the Air Force, while actors Robert Duvall, Danny Aiello, Tony Lip and Randy Jurgensen served in the Army. Harrison Ressler arranged and performed in USO shows during the War. Actors Abe Vigoda, John Marley, Richard Conte, Rudy Bond, Hank Robinson, Richard Matheson and Eli Wallach were all in the Army, while Al Martino, Harry Dean Stanton and Roger Corman served in the Navy. Actor Sterling Hayden was in both the Army and the Marine Corps, serving as an officer in the latter Hayden was also a secret agent during the War, serving in the OSS, the predecessor to the CIA. Spradlin, William Bowers and Paul Lambert served in the U.S. Author and screenwriter Mario Puzo and actors Michael V. Like the character Michael Corleone, many members of the cast and crew of 'The Godfather Trilogy' were military veterans, most of whom served during World War II. Paramount Pictures owner Charlie Bluhdorn read about the agreement in The New York Times, and was so outraged, that he fired Ruddy and shut down production, but Evans convinced Bluhdorn that the agreement was beneficial for the film, and Ruddy was rehired. The angry letters ceased after this agreement was made. He also agreed to hire League members (mobsters) as extras and advisers. Ruddy gave them the right to review the script and make changes. Ruddy met with Colombo, who demanded that the terms 'Mafia' and 'Cosa Nostra' not be used in the film. They threatened to protest and disrupt filming. Paramount Pictures received many letters during pre-production from Italian-Americans, including politicians, decrying the film as anti-Italian. According to Robert Evans in his autobiography, Colombo called his house and threatened him and his family. Mafia crime boss Joe Colombo and his organization, The Italian-American Civil Rights League, started a campaign to stop the film from being made. Eventually, Brando was crowned best prankster, designated by a heavyweight-style leather belt with the title, 'Moon Champion'.

They planned it carefully and Caan, who overheard the plan, started to shout, 'No, no, not here!' Everyone working on the production and most of the extras roared with laughter (some of the older ladies didn't appreciate the view). When I came out from behind the desk, I got a laugh, even though we had to do the scene over.' The ultimate moon came when Brando and Duvall mooned four hundred cast and crew members during the shooting of the wedding scene. So while everyone was looking at the shirt, I took off my pants. Even Al Pacino got in on the act, as he told Ladies' Home Journal, 'In a scene where I sit behind a desk, wardrobe made a big fuss about getting me a shirt with a smaller collar. Brando fell down in the car with laughter.' Richard Bright claimed that it got to the point where every time you turned opened a door, you expected to see someone's behind. Bob Duvall and I were in one car and Brando was in another, so we drove up beside him and I pulled down my pants and stuck my ass out the window. Caan told TIME Magazine, 'My best moon was on Second Avenue. In an effort to break some tension during a rehearsal for the first scene, the pair mooned Francis Ford Coppola, Marlon Brando, and Salvatore Corsitto. There was a great deal of mooning on-set, started by James Caan and Robert Duvall.

Godfather 1 movie poster