The intro with Kennebrew Beauregard that cuts between what he's trying to say seriously in his video, and him doing vocal warm-ups.
The phone conversation where Ron asks Duke how he knows if he's speaking to a white or black man. Duke says he believes Ron is a white man because of how he pronounces his R's and then goes into an example of how he thinks black people pronounce their R's. Ron's reaction is what sells it.
And then he throws it right back at Duke at the end when he reveals that he was the black cop assigned to the protection detail.
"Are-uh ya sure you don't know who he is?"
When Ron tells the sergeant about a Klan meeting being set up, he simply tells Ron, "You probably shouldn't go to that."
Philip (undercover as Ron Stallworth) goes to a Klan gathering at Felix's house. Felix, suspecting Philip of being Jewish, takes him into the back room and forces him at gunpoint to take a polygraph test. When he refuses, Felix tries to aggravate Philip by saying he believes that the Holocaust never happened and that Jews made it up as part of a conspiracy. Philip, who is actually Jewish, immediately attempts to one-up Felix by stating not only does he believe the Holocaust was real, but that it was the most beautiful thing ever.
Ron is assigned to be the police security detail to protect David Duke as he visits the town. As he prepares to leave he asks to get a Polaroid with him regardless of disagreeing with his stance. They end up asking "Ron" (Phillip) to take the picture, and on the count of three he surprises Duke and Walter by putting his arms around them, with the resulting picture showing them both as extremely uncomfortable. Later on, Phillip chastises him for the audacity, saying he, "nearly shit myself," when he did it. Even funnier is that apparently this picture was real.
During his first phone conversation with Walter, Ron gets everyone's attention due to using the n-word, declaring his hatred of black people, and weaving a story about his Aryan sister being touched by a black man. When he hangs up, the first words out of Zimmerman's mouth are, "Did I just hear you use your real name?" Even before giving a verbal response, Ron's expression is one of, 'Aw, man, he's right, I did just screw up.'
Before that, the dead silence that the room lapses into, broken only by the slow screech-screech-screeeeeeeeEEEECH of Flip's chair as he turns around in disbelief, his feet moving maybe an inch or two at a time. It's somehow way more funnier than if he had wheeled around in a dramatic double-take.
Immediately after Flip calls him out on his name slip, a phone can be heard ringing in the background that ends just before Ron responds. You can literally hear the alarm bells going off as Ron realises he screwed up.
This little gem from a black server working at the Klan's initiation ceremony:
"If I had known this was a Klan meeting I wouldn't have taken this motherfucking gig!"
When David Duke is talking about how a top scientist has "conclusively proven" that white people have the "blood of a superior race" and that it is an undisputed fact, you can see Flip standing next to him casting subtle glances in his direction that say "Is this guy for real?"
Topher Grace had problems finding David Duke's autobiography. He didn't want to buy it from a public store for obvious reasons, and as he told Seth Meyers, he had to confirm with Amazon that, yes, he fully intended to buy that David Duke's autobiography. Now he gets weird Amazon recommendations.