Afew times I've seen NPCs walking through the ceilings and floors, as if they're walking stairs even though the stairs are afew feet away. Another time the repair guy in the Stalker base floated slowing up from under the ground into his chair. Also I came across some dead bodies behind the space anomaly in Red Forest, one of the bodies was of Father Valerian however he's alive and well in the Stalker base. Edit: Another problem Wolf has gone AWOL.
Yes ive seen of couple of STALKERs pulling a Chris Angel thing i Loled at first starting to get odd as i see them walking through walls.
I also found wolf missing. I left on a sidequest. When I came back, he was back at his post. This was after I found his bro/significant other hiding from some dogs, then killing himself.