Keanu Reeves performed about 95 percent of the fight scenes himself. The only stunts that he didn't do are the ones in which John Wick gets hit by a car, and the one in which he falls down the stairs during the fight with Cassian (Common).
The Australian distributor, Entertainment One, or EOne, planned on not giving the film a theatrical release, and considered sending it straight to DVD. When news broke that the distributor was going to offload the film straight onto the home entertainment market, EOne's Facebook, Twitter and website were bombarded with e-mails and notes from angry fans, demanding the film be given a proper theatrical release in Australia. Shortly afterwards, EOne announced a nation wide rollout on April 20, 2017.
During the subway scene when John is being chased by two "janitors," you can see a graffiti drawing of a character (Chains) from the game Payday 2. After the first installment of John Wick was released, John Wick became a playable character in the game.
Ruby Rose's character Ares is never referred to by name in the film. Her name is only revealed in the credits to be Ares, though it also appears next to a photograph of her earlier in the film, in the Bowery's headquarters.
Despite the number of kills and public gunfights, there are no policemen seen throughout the entire film besides Jimmy, who was also the only police officer in the first installment. However, during one of the scenes set in Rome, you can clearly hear some sirens in the background, meaning that cops have been alerted and were sent to the place.
There are multiple references to the co-op action game "Payday 2", such as a scene where the Payday Clown's masks are seen as graffiti on a wall. The final contract's number, 11111, was also a slight nod to an inside joke of the Payday 2 community. In the game, John Wick appears as a playable character. When he was first released, he only had one line for when he collected a bag of loot, that line being "ONE!" this line would go on to become a joke among fans of the game as well as turn into a mod that replaced all of John Wick's lines with "ONE!".
The events in the movie are set in 2014, but the "accountants" are shown typing on a Commodore VIC-20 (with the logo blacked out) which is over three decades old.
The VIC-20 wasn't capable of the smooth text shown; its screen was limited to 176×184 pixels at its highest resolution. The green-on-black text shown is almost identical to the system screens from the Matrix.
When Aurelio breaks down the problems with John's car, he actually got some of his lines from the special effects crew members that helped smash the car, seeing that John Leguizamo was not present for those scenes and needed to be given some details.
Chad Stahelski and David Leitch mentioned in Screen Junkies interview how there were several different story ideas for this movie, including ones which would have him saving his daughter, or some love interest.
This movie was partially filmed in Montreal, Quebec. The city's architecture and various landmarks are visible during the film, including in the first scene, in which John drives past the "Scotiabank Theatre Montreal" on Saint Catherine Street, where the movie would be shown in 2017.
The Kimber 1911 that was given to John Wick could have also been supplied with a magazine of eight rounds of .45 ACP, instead of seven. Magazine design for modern 1911s can vary, based on the model of the magazine provided.
At 2 minutes 30 seconds into the movie, there is a Carl F. Bucherer advertisement on a large LED screen across the street from John Wick's car as he re-enters the car. Five seconds prior to that, one can see John Wick's watch as he reaches into the coat of his victim. He is wearing a Carl F. Bucherer Manero Autodate watch.
Throughout the film, the D'Antonio family is identified as being part of the Camorra, an Italian crime organization based in Naples. In real-life, Riccardo Scamarcio (Santino) is from the Apulia region, while Claudia Gerini (Gianna) is from Rome.
When John Wick kills Ares, he stabs her in the same place he stabbed Cassian; the only difference is that he removes the knife. This shows that he refused to give her the same "professional courtesy" he gave Cassian.
After John Wick fatally stabs Ares, she sits down and signs, "be seeing you John." This mirrors the climax of the first John Wick (2014), where after John fatally stabs Viggo, he sits and says the same phrase.
Although he receives third billing in the credits, and was featured prominently in the trailers, Laurence Fishburne has less than ten minutes of screentime, and makes his first appearance towards the ninety-minute mark.
The scene where John Wick is being chased in the subway system was partially filmed in the Place des Arts metro in Montreal, Quebec. The French signs were replaced with the typical New York City subway signs in English.
The film features multiple instances of religious or Biblical terminology. When John Wick first arrives in Rome, Julius asks him if his visit is connected to the Pope. The main villain's name is Santino, which translates literally as "Little Saint." Winston equates Santino's treatment of John to "stabbing the Devil in the back." The Bowery King refers to John's final showdown with Santino as a "descent into Hell." Finally, when John is expelled from the organization for breaking the rules at the end of the film, Winston refers to him as "excommunicado," in which a person is excommunicated (a status of exclusion and disfellowship) from the Church until repentance and reconciliation.
There are multiple references to Greek and Roman lore in the film. Lance Reddick's character's name, Charon, is a reference to the ferryman that shepherds souls to the underworld in Greek mythology. Ruby Red's character, Ares, was the Greek God of war. Common's character, Cassian, could be a reference to John Cassian, a Roman saint, or Cassius Dio, a Roman statesman and historian. Franco Nero's character, Julius, refers to Gaio Giulio Cesare (Julius Caesar). Willem Dafoe's character from the first John Wick (2014), Marcus, and John Leguizamo's character, Aurelio, combine to refer to Marcus Aurelius, a Roman emperor. Even John Wick's late wife, Helen, could be a reference to Helen of Troy.
One of the last scenes of the movie, in which John Wick meets Winston at the Bethesda Fountain in NY City's Central Park after Winston tells John that he is excommunicated and lost privileges, John asks why he is not dead already. Winston then signals one of his subordinates, who says "now" into a phone, causing every citizen in the park to freeze and look to John. This has glaring similarities to the scene from The Matrix in which Morpheus (Laurence Fishburne) talks to Neo (Keanu Reeves) about every citizen being a possible enemy (an agent); Neo notices an agent behind him and Morpheus tells the operator to freeze the program, causing every person in the scene to freeze in place. This scene also features a fountain.
In the sequence in which a contract is put on John Wick, a brief shot shows graffiti of a member of the Payday Gang from the video game Payday 2. A collaboration between the first movie, John Wick, and the game, Payday 2 was established as cross promotion.
At the end, Winston order number 11111 is the same number as JFK's executive order (executive order 11111). JFK's executive order on June 11, 1963 provided "assistance for the removal of obstructions of justice and suppression of unlawful combinations within the state of Alabama." November 22, 5 months later, JFK was assasinated.