This isn't the scariest image in the movie...it's the only one that's not too gruesome to display.
Unmarked spoilers below!
- Holy shit, EVERYTHING about the cavemen.
- First off, they're inbred beyond comprehension, coming from generations upon generations of inbreeding. This, coupled with the fact that they're cave-dwellers, has completely devolved them into subhuman troglodytes.
- Secondly, their barbaric appearances. They've jammed spiky animal bones into their faces and bodies, they're huge, hulking beasts of men that can tank through gunshots, and their bodies are covered with some sort of white ash that lets them blend into the sand and rock of their hunting grounds.
- Thirdly, their brutality. They seem obsessed with disembowelment and Groin Attacks, and their entire "culture" is based around rape, inbreeding, and cannibalism. They also love scalping and bare-handed bisections. The thing is, it'd be different if they were just animals who didn't know any better. But no, even though they have zero emotion, it's clear they do all this strictly For the Evulz. It's like they're trained to deliver as much pain as possible. Their culture is so gruesomely alien that it can't even be considered "Native American," no matter what their initial ancestry may have been: the Professor notes that the troglodyte tribe has no name among his people and that the native tribes of the area claim zero relation, culturally or ethnically, to the troglodytes. The one Pet the Dog quality the trogs do have is they apparently don't eat African-Americans, but the Professor implies this to be chalked up to base racism and the trogs are still more than willing to violently murder the stableboy during their raid on the town.
- The cavemen are so deranged and brutally violent that they sprint full-speed at people shooting at them without showing any sign of fear or self-preservation whatsoever. Like they are too primitive even to understand what guns are and what they do to people. But then their leader starts to figure them out...
- Then there's their weapon of choice, the bone tomahawk itself. Despite being made of solid animal bone, it's blunt enough to bust open skulls, yet sharp enough to decapitate with one swipe. And despite their apparent single-mindedness, are very good with them, to the point that when they don't use bows and arrows, they can throw them with deadly precision.
- The cavewomen. All of their limbs are cut off and cauterized, then spikes are driven into their eyes permanently so they can't see. They exist only to be breeding machines for the cavemen, spending their entire lives being raped, giving birth, and then getting raped again by their own sons in an endless cycle. And you just know that any daughters born suffer the same fate at the hands of their fathers or brothers.
- Think you're safe by running the hell away from them? Nope. Pervis makes a break for it whilst his partner is getting butchered and the cavemen follow him, all the way to Bright Hope. That's a several-day trip on foot or horseback and they still made it for the sake of one escaped man, and now the cavemen know about a community full of potential victims. As if they weren't bad enough already, the cavemen are Super-Persistent Predator and fully willing to seek out more prey.
- Finally, there's the noise they make, the only thing resembling communication they have. It's an unmistakably inhuman roar, and they pull this off by somehow wedging a strangely shaped windpipe made out of bone into their own throats.
- The description the Professor gives them sums up all their characteristics in one chilling diagnosis. Indians don't even consider them human;"They're a spoiled bloodline of inbred animals who eat and rape their own mothers."
- Nick's death. First the cavemen scalp him, then they shove his own scalp in his mouth and hammer it into his throat with a chisel. Then they hack through his groin with a tomahawk so they can bisect him with their bare hands. He's kept alive the entire time. You literally couldn't think of a worse death if you tried.
- Hunt's attempted murder. First they cut his belly open, then they shoot him in the arm when he tries to resist, then they force a metal flask that's been roasting over an open fire for hours into the flap. Then finally, they try shooting him in the groin (an example of how needlessly cruel and sadistic they are), but thankfully, this is before they figure out how to reload guns. "Before" being the key word.
- If you're squeamish towards throat slits, don't watch this movie. Literally the very first shot of the film is an excruciatingly long scene of a man's throat being cut. The noises are so disgusting. There's another one near the end of the film, and this one's even longer, and involves Arthur O'Dwyer carving open one of the troglodyte's throats to get at the bone windpipe lodged in his trachea.
- All those skulls and ritualistic sites the cavemen make? They're trophies, showing just how much the cavemen revel in their brutality. And when those trophies include bear skulls, you really understand what formidable hunters they are.
- The fact that the movie ends without any real confirmation that Hunt managed to finish off the tribe. That final gunshot? It could very well have been their doing.
