Visible crew/equipment: When Madison enters Bloomingdales, you can see the reflection of Ron Howard in one of the mirrors. (00:37:45)
Revealing mistake: Madison is wearing jeans as she walks towards the group of tourists although she's supposed to be naked.
Revealing mistake: When Hanks drives through the city escaping form the MPs, the guy driving is a very obvious stuntman.
Continuity mistake: Allen drives through a spotless park, but, when the angle cuts, a flock of pigeons appears ahead.
Answer: The sea hag gives Madison a set of instructions she has to carry out, and tells her that she can only survive out of the ocean for six days. She also tells her she has to wet her tail every day, which is why Madison is seen in the bathtub.
raywest ★
That's why she took a bath that night and got her legs wet turning them into fins.