I think this is actually intentional, but it makes some weird images, especially around areas with stairs. There were a couple of ghost heads at the bottom of the staircase after the pair of ratchet switches hidden by statues, that either couldn't get to me or weren't aware of me while I was at the top in the side area. Despite the staircase being mostly obscured at that point, including the bit they were standing on, I could still see them as though they were on top of the environment.
When I clicked the Activate in the last area, I expected some dialog or some action, but nothing really happens. I clicked it several times, thinking I did something wrong. Maybe show a sword placed on the stone? The Trojan fight is quite fun. I'm imagining new knights freaking out... awesome.