Monsters University
The movie was originally going to be named Monsters, Inc. 2: Lost in Scaradise. The movie would have been about Mike and Sulley visiting the human world to give Boo a birthday present. However, they find out that she had moved to a different house. After getting trapped in the human world, Mike and Sulley split up after disagreeing on what to do (Sulley wanting to look for Boo, Mike wanting to find a way to get back to Monstropolis).