Layout-wise: I suggest you make the paths a little less "straight". Even if you lose a little (~5%) horizontal sync, it'll look much more natural.
The terrain itself:
- The mushrooms are really out of place. See if you can find a green version, or tint it a little, and make them smaller.
- Although I like the orange glows, they are out of place. Make it more subtle, increase the transparency and size.
- Make use of terrain height, even if just for very small slopes.
Overall though, it looks good.