Continuity mistake: When Melody is in her room getting ready for her party, at one shot her hair is down. In the next shot of her, it's in a ponytail, and in the next it's down again.
Continuity mistake: When Morgana traps melody in the cavern, Flounder is seen in his younger size. The next time Flounder is seen he is back in his adult size.
Continuity mistake: When Morgana sinks Prince Eric's ship, he asks where Melody is and draws his sword. When Cloak and Dagger (the manta rays) pull him under the water, he no longer has his sword in his hand.
Continuity mistake: When Melody is singing for a moment, as she rises out of the sea on that huge whale, her green ribbon is missing.
Answer: She would only be going through that hole when she's swimming, but since she was walking on land there was no need for it. She could've gotten the boat and brought it to shore another way.