I think it was A17 (maybe) where iron arrows would get stuck in the air. In A20 (b233) one stopped my truck lol Burned rubber for about a minute trying to 'continue.' Finally turned in a circle and 'got by it.' Looked around at the ground and nothing there to halt progress of the truck; Then I looked down the road at a zed and there it was; stuck right were I was doing donuts. They also stick in mid air; IE: If you shoot a 'trap door' (that a zed uses to hid behind) +70% of the time it will still be there after the door is broken by it.