When Turbo and Boyka part ways, Boyka exclaims that Turbo didn't owe him anything. Turbo responds, "Where I'm from, ain't shit for free." In the previous film, "Iceman" Chambers said the same thing to the character Crot in regards to why Crot was helping him.
Boyka and Quinones have the same "Q" shaped tattoo. Boyka has it in his left peck while Quinones has it on his right forearm.
When Turbo tells Boyka that his first name is Jericho, Boyka happily proclaims, "you bring the walls down." This is in reference to the Biblical story of the Isrealites and the city of Jericho. (Boyka is a devout Russian Orthodox) In actuality, the walls of the otherwise impregnable city of Jericho were brought down by Joshua and his people.
Each fighter uses a particular martial art. Turbo is primarily a boxer but also uses jeet kune do, while Rodrigo Silvo uses Capoeira. Jerry Lam uses Tae Kwan Do, while Boyka, Quinones and the other fighters use variants of MMA.