They were set into the walls as if they were part of the walls themselves instead of stuck onto them. There were no latches or doors or hidden passageways. The long tunnel might have led to something, though -- it was long enough that there was possibly a door at the far end, hard to see because of the distance and the dark.

But now that Vance reached out to touch them, the mirrors changed. The reflections of Hal and Vance still looked like them -- except now blood was dripping from their hands in their reflections, even though there was no blood on their hands in reality.