There is an option where you can put the number of colors you used, to show on the submission. I'm too lazy to manually pick it out. It would make it much easier for me to critique your use of a limited palette. On that note, the hooves that are on the legs in the shadows have the same bright colors as the ones that are in the light. The front right leg(Princess Luna's right) could have some bright shades added to the leg to negate that issue, but the style I think you're going for, is for a flat consistent shading. Her back leg in the shadow can have the bright colors removed from the hoof.
Thank you Macaroni and Cheese! I will keep this in mind when/if I do any more ponies.