In the original draft of the GFII script, Tom Hagen was sleeping with Sonny's widow Sandra
Although that was removed, one line mistakenly was kept:
Michael (to Tom): Take your wife, children and mistress to Las Vegas
Also, the cat in Pt 1's opening scene was an improvisation by Brando; it was a stray in the studio parking lot.
The actor who plays Merle Johnson's actual name is Merle Johnson.
Both Vincent (when he hit the thug with a gun) and Sonny (beating up Carlo) actually harmed the actors.
When Michael calls to find out about the Don's condition, he dials Long Beach 4-5620.
The Sicilian hat worn by Michael's bodyguards is called a Coppola.
When the Don is angry at Johnny, he calls him a finocchio, the Italian equivelent of calling someone a ***.
When Michael speaks to the Turk in Italian, the Turk says:
"I am sorry. What happened to your father was business. I have much respect for your father, but your father... his thinking is old fashioned. You must understand why I had to do that. Now let's work through where we go from here." After Mike comes out of the restroom Sollozo speaks Italian again without subtitles this time saying, "Everything all right? I respect myself, understand? And cannot allow another man to hold me back. What happened was unavoidable. I had the unspoken support of the other Family Dons. If your father were in better health, without his eldest son running things, no disrespect intended, we wouldn't have this nonsense. We will stop fighting until your father is well and can resume bargaining. No vengeance will be taken. We will have peace, but your family should interfere no longer."
-The Deen
Sorry that it isn't chronological