Number one is that walljump before the big jump through lasers. Just change it to be similar to the walljumps later in the level.

The second thing is visual. You've got ancient road endings connecting to normal empire roads. The colors don't match and it looks crappy. I had the same problem at first.

The biggest issue to me is the portal on the saw at the end. Cool idea, but you might want to lower the portal (and presumably the saw along with it) down a bit relative to the edge of the track to make it easier for the first-timer to get through the portal. It took me several tries before I figured out how to get through it. This would also add the side-effect of allowing you to do a trick through the portal, which I personally would love. You could also just make the portal bigger.

The pillars in that end bit also don't stand out very well and are in general difficult to see because it's so dark. Maybe that's the point?

Finally - how much green is too much? I'm not really sure where to draw the line here, but I feel like it could be toned down a little bit.

So, take the suggestions or don't, either way great job and I look forward to what you've got in store for next time!