Some letters on the monster's skin?
Around the moment one of the creatures kills the Asian photographer, there's a close-up of its body where you can see some letters "painted".
What's with that?!
Yes! It's a link to the first scene in the movie where one of the guys that enter to the cave have tattos. The design is the same, the idea is that those guys became the creatures of the film...
Prostitute: What the *beep* are you doing?
Johnny: I'm gonna kill a bunch of people.