Trivia: The creature that hunts down the Doctor before being shot down by the Sniper girl is actually the original design of the Predator that was scrapped during Predator 1 due to issues with the costume and the jungle. The original Predator was supposed to be very slender with backwards knees and long arms, but because of the jungle setting, it was scrapped because the director was unable to make the costume work properly.
Trivia: At one point, the actor who played Nikolai whacked himself in the face during a scene and started bleeding. He ignored it, and apparently the blood added to the effect of the scene.
Trivia: When the Yakuza guy faces with the Predator, takes his shirt off and cuts himself across the chest, it's almost exactly the same as in the original Predator movie when the Indian guy faces down the Predator, takes his shirt off and cuts himself across the chest. And on both occasions, they die, although Yakuza guy manages to kill the Predator too.
Trivia: Hanzo has only three lines of dialogue in the entire movie.