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 famous line from the original Predator "You're one ugly motherf**ker" is included in Predators, but most people have missed it unless they speak Russian. Nikolai says the line before blowing himself up.