I think Seven-D nailed it with the ears, and while the model is looking great, to me it looks a little stiff (or very light).
The legs-feet-tail all work together as a giant spring, loading and unloading from one hop to the next. Tail maintains the momentum from the previous hop while the toes are on the ground (heel almost touching), then drops like a hammer as the spring uncoils in the next hop. Keeping in mind that most of the hop is mid-flight, comparing the other frames gives you a fair idea of the energy flow through the animal.
Not sure if you are still working on the project, but hope you are. Would love to see roos bounding by.