In the novel, Stracci's first name is Anthony; in the film it's Victor.

The air conditioner window unit at Clemenza's house.

Tom carrying his briefcase to his initial meeting with Woltz. Why?

Tattaglia whispering to an aide at the Don's meeting. Why was that in that scene?

Kay escorting her class' kids across the street. How did Mike know she would be there?

Sonny biting his fist when he sees Connie's black eye. I remember people doing that.

The long collar ends on Vito's shirt at the Don's meeting. Very similar to the Wiseguys in the "Analyze" movies and some other more recent gangster movies.