The water textures on the walls don't work. They're static and if you make an explosion near them, the explosion visually goes off behind the water brush even though it's actually out front. I remember hearing that water texture only works on the top of a liquid, which is supported by the fact that your map only has working water textures when they're showing the top of a pool.
Also, you should probably move the resupply cabinet. Where it is now, one of the doors clips through the pyro mask on the side of the team lockers (edit: on red side only, on blue side the same mask is stuck into the wall). And you can stand on top of the bay window structure in the cap area.
And some of your stairs (everything not around the point I think) aren't playerclipped. I point this out a lot, but it's a pretty easy thing to fix once you know it's there.
big edit: put a grate over the water in spawn, seriously. I assume you did a nobuild for the entire thing like any other respawn room, but check this out:
I don't think there's any way to fix that exploit other than to seal off the water (or petition valve). And while you're at it you might as well playerclip the ceiling in there.