Plot hole: When Nemo swims off to the boat, a diver pops up and catches him, and all the fish react. But this diver should have been visible to Marlin and co. long before it reaches Nemo, as they are far enough from the boat and looking out into open sea, yet none of them reacts until the diver is right behind him. Also, bubbles should have risen into shot before the diver does. (00:14:25)
Suggested correction: The fish were focused on the boat, not on divers that were toward the bottom of the ledge that they were at.