One particular attention to detail that I've always liked..

I liked the fact that this movie maintained alot of "realism" in their fights and also fighter's habits/behaviours which often gets neglected in other movies.

One particular detail I actually liked was how in in the final fight scene,
after George Chambers was trained in abit of MMA. He still PRIMARILY used boxing and only used some of his new learnt techniques.
Now THAT is REALISTIC and great attention to detail.

When a guy has been training in one particular thing for a long time, he develops habits into it. Once he learns new stuff, it's hard for him to integrate ALL of the things he learns immediately. In other words: When someone learns new things, they CAN'T use it all at once. They still prefer to use the old stuff they're used to and it takes a while to get used to the new stuff.

In this movie, they take this into account. George at the end of the movie still fights mainly as a boxer but used some of his new MMA grappling and groundfighting skills. He even acts like he hasn't completely adjusted to some of his new skills.

If this had been some other typical b-grade martial arts movie crap. They wouldn't have this kind of attention to detail and would have some stupid unrealsitic BS like how a person can train in martial arts for just 2 weeks or a month and suddenly pull off moves like they've been doing this all their life.

You gotta appreciate the little attention to detail they put into this movie because sure as heck many other movies don't.


Edit:

Another similar attention to detail in fighter behaviour/reaction is during their first fight when Boyka says he will only use fists against Chambers, but later switches to using the full set of MMA once he got beaten up the first time.

Boyka starts kicking Chambers in the shins, in which Chambers didn't know how to react or counter the move. Good realism.

Being primarily a boxer, Chambers wasn't used to kicks AND also his opponent hitting below the belt. In doing Shin/low kicks, Boyka did both at the same time.
Two things which would also reastically affect a real boxer who has only primarily fought against other boxers.

Again, nice attention to detail.