In the cave area images the concrete (metal?) wall textures need to be moved down a little, they're misaligned to the floor.
Loving how the shadows are turning out, but make sure not to overdo it as low lightmaps can kill your performance.
Also, Elevators=not good in Source, maybe the shafts and cars are accessible but static? There are just so many things that can go wrong with elevators, including all of the I/O stuff, then it likes to lag and glitch up when being used online.