Similarities to Other Movies...
1) Moana reminded me of Rapunzel in Tangled. Forbidden to leave a certain place, on a journey with a reluctant anti-hero/thief, even some of the facial expressions.
2) Maui's tattoo-man reminded me of Kronk's shoulder angel and devil. Similar idea of a mini version of him advising what to do or commenting on what he's doing.
3) The crab kinda reminded me of the crazy crab in Shark Tale. Not quite sure why, though.
4) Similar plot to Lord of the Rings. As in, "Put that thing back where it came from, or so help me" the world will be taken over by darkness!