When Nori is talking to the Merfairies, she turns around and puts her hands on her hips at the sight of Elina, but when Elina approaches her, her arms are crossed.
When Elina, Nori, and Bibble are in the Magic Sea Fruit Cavern, Bibble eats fruits that change his voice in a hilarious way. When Elina asks Nori how long the effects will last, Nori's Crest Of Courage disappears for a brief moment.
When Bibble eats the fruits that change his voice, the arrangement of fruit on the branch he picks it off from constantly changes.
When Elina and Bibble are at one of the MerFairies' house, the MerFairy grabs Elina a plate of food that has brown handles on the sides, but in an overhead shot, they disappear. They reappear when she places in it on the table.
The objects thrown by the main characters near the end of the film should not have moved as fast as shown, or have had hit the fungi as hard, since they are underwater.
Whenever any character gets out of water, they never show signs of ever being wet.
When Elina first mets Nori, waterfalls can be seen everywhere, but they don't make sounds.
Elina is never seen or heard eating the special seaweed that enables them to breathe underwater.
When Delphin gives Elina the pearl necklace, she says they will turn deep blue, then turn white one at a time. However, in the film they actually turn white, two at a time.