Corrected entry: In the scene where Ariel is watching the people on the ship Ariel says to Scuttle "Not that one, the one playing the snarfblat." (Snarfblat is a pipe) the person that Ariel would be talking about (Eric) doesn't have a snarfblat, and even if she was talking about Grimsby (who does have a pipe later on in the movie) who at that point in time he doesn't have one ether.
Corrected entry: When the wedding is taking place, the priest's cross turns upside down for one frame.
Corrected entry: When Scuttle flies into Ariel's room at the castle on the third day, he tells her and Sebastian that the whole town is already buzzing with the news that Eric is getting married that afternoon. But it's not decided that the wedding will be then until a few seconds later - Ariel and Sebastian see Eric instruct Grimsby that he and Vanessa wish to be married that same afternoon.