The ending sequence with the manta is hugely reminiscent of some of the old Windsor McCay Little Nemo in Slumberland comic strips from the 1920s, though I'm not sure why.
Also, folklore facts! This kind of salve shows up in traditional fairy stories in Britain — the best known involves a woman who steals some (not knowing what it does) from her friend, who is supposedly a witch, and rubs it on her left eyelid — and suddenly, with her left eye, she can see fairies. Later, she meets a fine lady that she can only see with her left eye and bows to her; the lady is shocked and asks which eye she's being seen with.
"My left eye," the woman answers — and the lady reaches out and, *snatch!* And, well, the woman never did see fairies with her left eye again — or anything else, for that matter