Commentary Time! Image captions are on top of the image it is describing. Here are my suggestions, hopefully you'll take these into account by b1.
1. Disable fog in your map, it looks so much better without it. To see what I mean:
With fog. Notice how the smoke is not fogged, which makes it look odd, unnatural, and plain ugly.
Without fog (achieved with fog_override 1 and fog_enable 0). Looks MUCH better, however, now some of the things in the skybox render as black from afar (which can be remedied easily). See for yourself.
Yeah, some stuff fades to black, only if it's in the skybox however. Experiment with it.
2. The cart should do a 180 degrees turn when it switches sides at the middle point. What I mean is that when it gets to the middle point the cart will turn around (gradually, not instantaneously flipping over) and then keep going. You can also have this in the beginning at the middle so that the cart starts turning to the opposing base as you cap it. This means that the cart will start off horizontally and neutrally, facing no teams base, and as one team starts capping the middle point, the cart will gradually rotate to face the opposing team's base. This will mean you'll have to create a model and functions for that kind of stuff, I suppose. However, it would make your map a whole lot better.
3. The cart is skinned blue in a6. Whoops!
4. Disable the shadows for these props in the following pictures, or check your lighting on the walls in these pictures. Some of them have unnaturally weird shadows. (oh, and check the same places in the opposite base as well, they might have the same problem).
This is a double-whammy: The garden hose and the shadow underneath the loudspeakers.
5. I've seen a red version for these turbines in your red factory pic (copy-pasted here just for reference). I don't know if they're official or not, but I've seen them, and I'll look for them.
I'll update this post with more things I find.