hmm.

Dylatov: Damn, what's that light?

Yuri: Looks like they're testing nukes over there.

Alexander: And shit, we're lost. We're high up on the mountain, not over the pass.

Dylatov: Damn, let's just camp here.

Yuri: I'll start a fire.

Alexander: Wait. We can't prepare food out here if they're shooting off nukes dude, it'll rain radiation on it.

(all are beginning to show mental exhaustion and need a hot meal and a long rest)

Dylatov: Ok, no fire. We eat cold rations tonight, but not too much, we'll get hypothermia.

All: Fuck that, we're hungry.

(later - hypothermic hallucinations have set in)

Someone: Damn, i'm building a fire.

Someone else: But you can't do it outside the tent because of the lights in the sky.

Someone else: Do it over by the treeline where there's some shelter from the fallout.

Someone else: I'll help

Someone else: I'm already too hot, I'd better take off these clothes

Someone else: I'll help

Someone else: No get away

(tent rips)

Ok, this is low budget:

(camera pans away to the dark night, shouts and screams ensue, crying, sobbing, fading snow-crunching footsteps, sudden silence)

Ok. Since their bodies froze almost at once there may not be any soft tissue damage detectable via usual means.

If military tests were going on there (cf the 'orange globes' seen in the area about that time) then clothes left outside could be dusted with fallout.

The weird tan and missing tongue could have been as explained in the Cracked article.

tl;dr most of the weirdness is from the corpses being frozen, and the rest from nearby nuclear tests