Elevation

C'mon, folks, you can't be a serious person and think this movie isn't trash. The problem is, it's a bit difficult to explain exactly why without using spoilers. But I'll try.

Well here's a shortcut to explaining why: Plot holes abound. People do stupid stuff that makes no sense. Stuff you know they wouldn't do (or be allowed to do) IRL.

This isn't a spoiler since it's revealed at the very start of the movie: The "creatures" don't ever go an inch above 8,000 feet of elevation. This is clearly absurd, and is never explained. Oh, and someone very nicely marked the 8,000-foot elevation line on an entire mountain range, and they did so with hyper-precision. So much precision, in fact that you can lie down and rest just beyond the marked line even if there's a creature that was just bearing down on you, because the creature will stop in its tracks. Absurd.

Splash in all the usual contrived garbage, sprinkle in a bunch of nonsensical plot absurdities, and top it off with a laughably absurd conclusion.

And nothing is ever explained. I guess they looked at the garbage script they had and rightly decided it wasn't worth explaining. Good call.