Looked at the hiring scene again and though the animal might look like a sort of jackalope, the horns ain't right. They don't look like antlers and the ears don't look like those of a rabbit. I think that question (#2) has yet to be properly answered.
I beg to differ:
Since the Jackalope is a mythical creature, it can take various forms. Often it's a Jackrabbit with antelope horns, thus the name. But it can also have deer antlers, as in your pic. The jackalope in Aguirre's trailer is a mountain hare with antelope horns.
Pet rabbits often have hanging ears, there are breeds specialised in it, so I guess the taxidermist has chosen to make the ears hanging. I think the genetic disposition for this mutation must be latent in the wild forms of rabbits, and probably also in hares. So maybe there even are some wild hares running around with lop ears, who knows?
