The presence of the Black Predators. We know that the Predators are divided into Clans who are united by shared rules of combat, with the Classic ones who have been thus far depicted in the movies and Expanded Universe. So what happens to those who reject that philosophy? Is it possible that the Black Predators are the Stans and Edwins of their culture, who were sent to the planet as game, but managed to overpower the Classic ones sent to hunt them?
Or the other way around. The Black Predators have enough resources on hand (the "dogs", the flying drone) to suggest it's their hunting ground; the Classics might've arrived to disrupt their hunt, only the Black clan got the jump on them, tied one up as bait, and wiped out its companions one by one as they tried to rescue the prisoner.
When Stans is talking to Edwin about "bitch raping time", he's not referring to women.