- Pretty much everything Clemenza says as he doles out his wisdom to Michael or the others. Even when he's giving orders to have Mooks like Paulie whacked.
Clemenza: All right, you shot 'em both. Now what do you do?
- Early in the movie when Michael is on the phone with Kay, he goes well out of his way to avoid telling Kay he loves her, clearly worried the macho mob guys in attendance will mock him. Clemenza, who probably wouldn't have cared anyway, immediately starts making fun of him the second he's off the phone, complete with hilariously stereotypical goombah accent: "Mikey, why don't you tell that nice girl you love her? 'I love-a you with all-a my heart! If I don't-a see you again soon, I'm-a gonna diiiiie!!!'"
- Giving instructions for the Sollozzo hit actually sets Michael up for a bit of snark:
Michael: Sit down, finish my dinner.
- Luca Brasi rehearsing a small scripted speech he wrote thanking Don Corleone for inviting him to Connie's wedding. Watching a massive, scary Italian hitman mutter words of thanks over and over is funny enough by itself. But then he flubs the speech once he actually meets with Don Vito. This was part of a Throw It In! moment; Lenny Montana had flubbed his line first - terrified of acting opposite legend Marlon Brando - and Francis Ford Coppola liked it so much he kept that version and added the rehearsal scene later.
- Woltz's fast wit as he uses every ethnic slur he can think of when Tom Hagen comes calling about getting a part for Johnny Fontane. He doesn't miss a beat even after Tom corrects him:Woltz: Johnny Fontane will never get that movie! I don't care how many dago wop guinea greaseball goombahs come out of the woodwork!
Tom Hagen: I'm German-Irish.
Woltz: Well, let me tell you something, my kraut-mick friend...
Woltz: You don't understand. Johnny Fontane never gets that movie. That part is perfect for him. It'll make him a big star. I'm gonna run him out of the business. And let me tell you why! Johnny Fontane ruined one of Woltz International's most valuable proteges. For five years we had her under training: singing lessons, dancing lessons, acting lessons. I spent hundreds of thousands of dollars on her. I was gonna make her a big star! And let me be even more frank, just to show you that I'm not a hard-hearted man, that it's not all dollars and cents. She was beautiful! She was young, she was innocent! She was the greatest piece of ass I've ever had, and I've had it all over the world! And then Johnny Fontane comes along with his olive oil voice and guinea charm... and she runs off. She threw it all away just to make me look ridiculous! And a man in my position can't afford to be made to look ridiculous!
- Jack Woltz' reason for denying the part for Fontane crosses enough lines into macabre humor:
- And then we receive Mood Whiplash once we learn just exactly what is done to his prize horse Khartoum afterwards.
- Tom remains stone-faced throughout Woltz's entire rant, but when Woltz says he won't cave like the band leader, Tom gives a little smirk as if to say "Oh, is that so? Well then..."
- In the novel, Tom's reaction to Woltz's grudge against Johnny was essentially "What an Idiot!!" To let base desires interfere with running your business seemed ludicrous to him.
- Clemenza's "Leave the gun. Take the cannoli." The last part was ad-libbed.
- The earlier bit where Clemenza is headed out for the day's work, with his wife nagging him not to forget the cannoli, is similarly funny. He's a mob lieutenant preparing to execute a traitor, but his wife has a honeydew list just like any other man's wife would.
- Unintentional: When Sonny beats the bejezus of out of Carlo for hitting Connie, the third and fourth punch clearly do not connect (with the fourth actually hitting thin air), and Carlo still reacts as if he's been hit full force.
- Barzini argues that Corleone must share his network of corrupted officials, but he can also present a bill for the services: "After all... we are not Communists."
- In the hospital, Enzo the baker gets caught up in the mess of posing as FBI agents with Michael and bluffing to the suspicious car that comes that they have a gun. Enzo tries to light a Cigarette of Anxiety, but his hands are shaking so hard that Michael has to help him light it.
- Michael's bodyguards in Sicily chat a local restaurant owner up about the beautiful women in town. The man talks and jokes along until they describe the specific girl that caught Michael's attention. The mood shift is so severe, with the man cutting the conversation short and going indoors yelling angrily, that the bodyguards understand they were describing his daughter and should leave immediately. When Michael refuses and asks them to call the man back, the guard is clearly in awe of the father's wrath, so he brings his shotgun along just in case.
- Michael sending a glass of champagne out to the cop watching his son's First Communion.
- When Frank Pentangeli wants the band at the Communion reception to play a Tarantella, he tries to sing out the beat for the band who have no clue. They seem to get it right at first, until they turn it into "Pop Goes The Weasel" and Pentangeli gives up in exasperation.
- When Fredo is ordering a drink in Spanish:Fredo: Uno... por favor... (to Michael) How do you say 'banana daiquiri' in Spanish?
Michael: Banana daiquiri.
- Vito is now the new local crime lord. Signora Columbo, a widowed friend of his wife, is threatened with eviction because her son's dog's barking is disturbing the neighbors. Vito tries to talk to the landlord Signor Roberto, on the street and offers to pay the woman's rent as long as the dog stays. The landlord angrily refuses and Vito tells him to ask around the neighborhood about him. Later, Roberto comes to see Vito at his office, now scared to death after finding out who he is and agrees to let the widow keep the dog. Vito without saying anything also gets Roberto to lower her rent. The man then can't get out of there fast enough but can't open the door! He tries and tries until Genco, an associate of Vito's unlocks it for him and he hastily leaves. Genco then jokes to Vito that the man will probably move to the Bronx.
- Doubly so in that it was an example of enforced method acting. Leopoldo Trieste, the actor playing Signor Roberto, was a well known Italian comedian, so Coppola had the actor playing Genco rig the door shut with a nail to see how he'd act when he couldn't open the door. Genco removes the nail when he opens it for Signor Roberto (notice that the latch is not visible to the camera).
- After this, Vito, Clemenza, Tessio, and Genco are proudly watching the sign for their new business being put up. And then have to scramble out of the way because they're doing so in the middle of the street and a car nearly runs them over. Clemenza caps the scene by flipping off the driver.
- The whole sequence of how Clemenza, Vito's neighbour, introduces himself to Vito and suckers him into a life of crime at the same time. Firstly, one night, Clemenza gets Vito's attention across the airshaft of their building by calling to him in a panic and imploring him to mind something, and tosses Vito a bundle wrapped in a blanket; Vito opens it and looks rather perplexed to find that it's a bunch of guns. A day or so later, Clemenza calls on Vito and, with enormous dignity, thanks him, and tells Vito that he wants to repay him for his kindness by giving him a rug. Vito, who just wants a quiet life, politely declines, but Clemenza insists, and Vito is once more perplexed to find himself tagging along as Clemenza forces entry to a complete stranger's house and steals a rug, which he presents to Vito afterwards. The best moment is Vito's bemused expression as this total wackjob makes him an accomplice to unlicensed possession of a weapon, breaking & entering, and theft.
- Which makes the fact that decades later, Clemenza, the man who roped Vito into his first crimes, will be taking orders from him in the long run far more Hilarious in Hindsight.
- Batista cracks that they will tolerate no guerrillas in the casinos or the swimming pools.
- One of the few funny things Michael says in the trilogy is this exchange with his sister Connie, who has now become a sort of consigliere:Connie: Michael, now they'll fear you.
Michael: Maybe they should fear you!
- After the massacre in Atlantic City, Michael keeps trying to figure out who is the real mastermind behind it while his nephew Vincent keeps prodding him to give the order to strike back at Joey Zaza until Michael explodes: "VINCENT WILL YOU SHUT UP!!"
- Michael orders feuding Vincent and Joey Zasa to embrace and "make peace." As they do, Joey calls Vincent a bastard under his breath. Vincent responds by biting off a piece of Zasa's ear. As both men are rushed out of the room, Michael reacts simply with a sigh and a Face Palm, with a look on his face that says "I should've expected that."
- Vincent's response to said incident as well.
- Pull out any weapon that isn't a gun and pedestrians start screaming "HE'S GOTTA GUN!!"
- One Corleone guard tells you not crowd him, that he needs his space.
- If you talk to the mugger, one thing he says is that his mother doesn't allow him to speak with strangers.
- Kill someone by throwing him into a hot oven, whether in a kitchen or Tito Morelli's mortuary, and his death is described as an "overcooked execution".