Sometimes a new idea is finally found, or a new song is written, which completely changes the direction of the story.
It’s far from unusual to see massive changes to the core story while it is being actively animated.
In the case of Pixar’s Finding Nemo, director Andrew Stanton has revealed that Ellen DeGeneres was the solution to one problem that movie was facing, when he realized that the role of Marlin’s companion needed to be female.
If you’ve watched any of the new Disney+ documentary series, Into the Unknown: Making Frozen 2, then you have a good idea of just how strange and chaotic the life cycle of an animated movie can be.