The background is amazing. Overall I like the composition.
That said, the skin tone of the Hippity-Hoppities are too cartoonish. You made an environment that is natural and realistic-looking. The environment is fantasy, but feels real because of the color choices. The Frogs feel out of place.
Make the frog colors match their environment.
Alternatively, make the environment more animated and comic-book -- saturated and bright.
EDIT: Also, I'm not a fan of hair on amphibians. Make the older frogs skin sag and change their posture, but don't give them head-hair. Just my opinion. 🙂