Trivia: The infant playing Connie and Carlo's baby son Michael Francis Rizzi who Kay holds during the christening scene is Sofia Coppola, Francis Ford Coppola's daughter, who was born in May 1971. Sofia later had a prominent role in Part III as Michael's daughter, Mary. Other than the main characters, Sofia is the only actor to have appeared in all three films. In The Godfather II, she can be briefly seen as an immigrant girl on the ship that brings Vito Corleone to Ellis Island.
Trivia: Marlon Brando won a Best Actor Oscar for his role as Vito Corleone. Robert DeNiro, who played the role via flashbacks in Part II, won a Best Supporting Actor Oscar. They remain the only two actors to win Oscars for playing the same character. Heath Ledger and Joaquin Phoenix both won for playing the Joker, but not really the same character, given the very different films and portrayals.
Trivia: Johnny Fontaine was envisioned by Coppola as a young Sinatra, and was played by singer Al Martino. Martino didn't have much acting experience and was having difficulties getting his expressions and emotions right when the camera was on him. So, when he is in the office with the Godfather, the reason the camera is so often at his back is because he felt uncomfortable and unable to do the scene with the camera focused directly on him.
Trivia: During the shoot of the movie, many people were unhappy about the quality of acting Pacino was giving. They thought he was showing the character as dumb and slow-witted. It wasn't until the scene of the Sollozo murder, on the third and fourth day of shooting, that the big heads at Paramount saw "quality acting" on Pacino's part. However, Pacino was still not highly regarded until the Godfather became a big hit, and Coppola was criticized immensely, and was threatened to be fired for his cast choices and the manner in which he was filming the movie.
Trivia: Originally the character of Connie was supposed to be played by someone Coppola called "plain looking, the daughter of a big-shot who is only married off because she's the daughter of some big Mafioso guy". When they couldn't find an actress, Talia Shire, Coppola's sister, got the part, even though Coppola thought she was too beautiful and said "C'mon, look at her. Who wouldn't want to marry her?"
Trivia: In the scene outside the hospital when Michael encounters Capt. McCluskey, the officer standing to the left of McCluskey, "Phil" is actually former legendary New York City police officer, Sonny Grosso. Grosso was the actual partner of Eddie Eagan, who was portrayed by Gene Hackman as Popeye Doyle in "The French Connection" (1971). Grosso's character, Buddy "Cloudy" Russo was played by Roy Scheider. Grosso went on to direct and produce numerous police dramas for TV (the best known is "NYPD Blue"), usually about the New York Police Department.
Trivia: Surprisingly, the word "Mafia" does not appear in the screenplay once. Apparently, the Italian-American Civil Rights League had an agreement with the film's producer not to use the term "Mafia" in the film.
Trivia: The horse's head that was cut off and placed into Woltz's bed was real - it was from a slaughterhouse. They painted on the stripe and added the fake blood.
Trivia: When Luca Brasi goes to visit the Tattaglia's and is strangled, you can see his face turning slightly black due to strangulation. This effect was achieved by placing a type of translucent powder on the actor's face which tints black when it comes in contact with water. So while Luca Brasi was being strangled, a fine mist of water was sprayed over his face to trigger the colour change.
Trivia: The scene where Connie breaks the dishes and vases and then Carlo beats her up was originally not supposed to be in the movie; Coppola tacked it on because the studio felt the movie didn't have enough action and were about to bring in an action movie director.