Facts like those?
Running around in the dark half crazed and running into rocks etc could explain the injuries.
Three of them had fatal injuries: the body of Thibeaux-Brignolle had major skull damage, and both Dubunina and Zolotarev had major chest fractures. According to Dr. Boris Vozrozhdenny, the force required to cause such damage would have been extremely high. He compared it to the force of a car crash. Notably, the bodies had no external wounds, as if they were crippled by a high level of pressure.
Of course the skeptic ignores the autopsy report about the injuries, comes up with a flimsy excuse, blames Soviet paranoia or claims it wasn't part of the original documents. Or maybe they did have a secret hidden car and crashed, who knows
You've always gotta have at least one skeptic in these kinds of conversations, and I didn't see anyone else stepping up to the plate.
Anyway, here's my contribution:
http://en.wikipedia.org/wiki/Rongorongo Okay, nothing creepy about this one, but it is still a mystery. If it turns out that it is a form of writing after all, then there's the possibility of someday deciphering it, and then we'll learn more about that civilization. Unless it turns out to be purely decorative. Or impossible to decipher.