- You can build inside first red-spawn
- You can walk into the sliding spawn-doors with pretty much any class just by trying to exit (They move too slow and should be flagged for "non-solid to player")
- You can get on-top of this clipping.
- The textures here arn't rotated correctly.
- You can sort of get out the map here due to clipping not reaching the skybox.

In general the map needs a lot of work, it's very claustrophobic and close together with quite linear paths and questionable clipping. It's quite small for a payload map also. But don't be put off, it seems like you tried well with the map and I think you could do better.