I think they should have swapped the final opponents for the brothers.
It would have made more sense for Chad to go after Zhang and Alex to go after Griffith. Chad had the earlier encounter with Zhang when Zhang mistook him for Alex and tried to get him to smuggle the drugs for him whereas Griffith had been a threat to Alex's girlfriend Danielle. Additionally, the two styles in which the fights took place were somewhat of a reversal. Whereas Alex had been the one to use a gun and Chad had been the one to fight more with his hands and feet, we ended up with Chad dodging bullets and Alex going hand to hand with Zhang.
It could have been done intentionally to switch things up a bit, or to show that they're in it together and so it doesn't really matter who goes after who, but I really think it would have made for a better ending if they had each gone after the opponent whose role in the film and manner of fighting most befitted them personally.