Viggo: I heard you struck my son. Aurelio:Yes sir, I did. Viggo: And may I ask why? Aurelio: Yeah well, 'cause he stole John Wick's car, sir, and uh... killed his dog. Viggo:[long pause]...Oh.[hangs up]
This becomes a Brick Joke moments later when Viggo is explaining to Iosef exactly who he mugged.
Viggo Tarasov: Oh? How do you plan that? Iosef Tarasov: By finishing what I started. Viggo Tarasov:[irritated, turning to Avi] What the... did he hear a fuckin' word I said?
Viggo's "conversation" with John, which consists of him trying to placate and talk John down from going on his inevitable Roaring Rampage of Revenge, while John listens in stony silence and then hangs up. The periodic switches from Viggo's placation to John's emotionless face heighten the effect.
After the fight at his house, John calls in a "dinner reservation for 12", which is code for "I have twelve dead bodies to dispose of". Charlie and his men show up, then politely clean up every last drop of blood (and wrap every body up in sheets, then cart them off in a van) in a very tidy manner. Every member of the crew is huge, intimidating guys, who are mopping and cleaning windows, along with them being led by the comparatively tiny Charlie. And all to a hard rock tune that wouldn't have been out of place for the fight itself.
Given a Brick Joke later on. When John's fighting Perkins in his hotel room, the phone starts ringing over the sounds of violence. After a few seconds, there's an abrupt cut to the very quiet lobby of the Continental, with Charon patiently waiting for John to answer, even though he clearly knows what's going on. This happens again before John wins the fight and picks up the phone.
John: Yes? Charon: I apologize for calling you at this hour, but we have received a number of grievances from your floor concerning the noise. John: My apologies. I was dealing with an uninvited guest. Charon:[casually] Have you need then of, say, a dinner reservation, perhaps? John: Perhaps. I'll have to get back to you.
Similar to Jimmy, John has a brief conversation with Francis, the bouncer for Viggo's nightclub. After getting an answer to the number of guards inside, John "suggests" that Francis take the night off, and Francis is all too glad to take it.
Avi, Viggo's consigliere, repeatedly having to ask Viggo to speak in English to him, much to Viggo's displeasure.
John walks into a church and, when greeted by the priest, wordlessly whips out an assault rifle. Everyone, including the freaking organist, pulls out a gun only to be shot down by John, leaving only the kneecapped priest angrily cursing at John and a bewildered little old woman who seems to be the only person in the entire building who's actually using the church as intended.
Also, when John demands the priest open the security gate to Viggo's vault:
Priest: Viggo will kill me! [John executes another guard] John:[beat]Uh-huh?
The priest yelling "MOTHERFUCKER" after he is shot by John.
During the confrontation in the church, Viggo points out that their career choices haunt them and cling to them in a very dramatic speech.
Viggo: We are cursed, you and I. Wick: On that, we agree. [Beat] Viggo:[brightly] Finally, common ground!
A while thereafter, John grabs a Kel-Tec KSG shotgun and ends up wrecking Viggo's car entourage single-handedly within a handful of seconds. When he turns his gun to Viggo, Viggo just says "Coolitcoolitcoolitcoolitcoolit!" in the most hilarious manner possible.
Per the directors' commentary, this line was ad-libbed by Michael Nyqvist.
While on the subject of Viggo, there's Viggo going full Villainous Breakdown and refusing to hand Avi a gun in the most childish way possible.
The start of his breakdown can also be seen as one. When John explains that the dog was a final gift from his dead wife whilst being interrogated by Viggo, you can see Viggo start to completely unravel, as if he's thinking "Oh, fuck. It's even worsethan I thought."
A meta one, the directors were quite nervous that Alfie Allen would refuse to film the scene where he runs through a crowded nightclub in a towel, not having seen Game of Thrones where he'd gone through far worse indignities.
Also, Iosef is essentially the same character as Theon: a spoiled clueless prince who can't measure up to his father.
Another meta moment: the fact that Avi is played by Dean Winters, best known as Mayhem from the Allstate commercials. Considering all the damage John does in the movie, they're gonna need a very understanding insurance company.