Royce: What's the last thing you remember?
Cuchillo: All of a sudden, there was a light. And then, I was falling.
When Royce kills the Predator at the end, he slices the head off, and it falls backwards, and the body falls forwards. One of the next shots now shows the head to now be in front of the Predator body.
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.