> Also, the dog / rabbit dynamic (as used in the classic dog/duck/grain river crossing puzzle) made me think that I had to chase the rabbits with dog, or that dogs and rabbits couldn’t share a node.

Yes, I assumed first that no two animals could share a node at all until I was near the end (and saw that it would be necessary), and I still assumed that rabbits and the dog couldn't share a node ("the dog will eat the rabbit!") because of the river crossing thing, until someone in this very comment thread mentioned an unsolvable state that involved getting the dog a rabbit on the same node.