Well over at sci-fi.com they've done an article about Carsten Norgaard injuring himself:

"Carsten Norgaard, who plays an oil driller in the upcoming SF crossover movie Alien vs. Predator, told SCI FI Wire that he broke a rib filming a fight scene with the Predator. "It was a scene where I get punched seriously," Norgaard said in an interview. "I was pretty much out of air when the first big hit happened. I felt something. We had to take a recess for 15 minutes and kept on going.""

Check it out -Thanks to AVPGalaxy