Clemenza telling Michael that they were all proud of everything he did during the war, including his father.
After Sonny's death at the tollbooth, Don Vito has Tom call the mortician Bonasera to repay the favor he owes. Bringing Sonny's body to funeral parlor, Vito begs for the favor:
Vito: I want you to use all your powers, and all your skills. I don't want his mother to see him this way. (he pulls away the sheet to reveal Sonny's bullet-riddled corpse. After a moment, Vito begins crying)Look how they massacred my boy...
Subverted in Part II, near the end when Mama Corleone passes away and Connie talks Michael into forgiving Fredo for his accidental betrayal. Michael comes out of hiding and hugs his grieving brother... only to coldly look up toward Al Neri, who nods quietly back to his Don. This is the Darker and Edgier sequel: Michael's not about to forgive anyone...
Michael and Sonny's last scene together before he goes off to kill Sollozzo and Sonny's promise to let Kay know when the time is right.
Vito saying to Michael "I never wanted this for you." combined with their prior discussion of Michael's 3-year old son reading the funny papers.
After Sonny's death, Hagen is shaken and goes to pour himself a drink. Don Vito walks in and Tom scrambles to the effect that he was about to waken him and let him know. Vito initially reproaches him, but later on, he embraces Tom.
"You've been a good son. You comfort me." Telling Hagen that he had acted properly in this terrible time.