Chad Stahelski director and script writer included some Latin phrases into dialogue.
Jhon Wick as film it is unique in action, drama and characters. I always say, dialogue is a wit of cinema. Jhon Wick is more than a film. Audience has chosen Jhon Wick 3 over Avangers end game means they love the film.
Dialogue has always been a pivotal part of cinema. As a linguist I have noted down some words and phrases which has shaped the style of film.
Parabellum – meaning “If you want peace, prepare for war.”
Charon: Do you expect him to make it out?
Winston: A fourteen million dollar bounty on his head, and every interested party in the city wants a piece of it, I’d say the odds are about even. ( Here the meaning is – An opportunity in which the chance of success is equal to that of failure.)
Switch Board Operator: John Wick, excommunicado (“put out of the community,” which is just what happens when a person is excommunicated.) . In effect, ten minutes.
John Wick: I will serve. I will be of service.
The Elder: Very well, my son. Cast aside your weakness and reaffirm your fealty (formal acknowledgement of loyalty to a lord.”a property for which she did fealty”) to the Table.
The Adjudicator: [to Winston] You gentlemen, of course, realize that was the first wave. Merely an amuse-bouche. (These, often accompanied by a complementary wine, are served both to prepare the guest for the meal and to offer a glimpse of the chef’s style. The term is French and literally means “mouth amuser”. The plural form may be amuse-bouche or amuse-bouches. ) We can keep this up as long as you’d like, but it only ends one way.
I am sure, the new phrases are more stylistics and they will soon get absorbed into regular English. Check my link.