2. The reason the name on the diver's goggles is P. Sherman is due to the fact that a large part of the film's crew was Filipino, and "fisherman" apparently sounds a lot like "P. Sherman" in a Filipino accent:
4. The movie originally didn't start out so sad. The death of Nemo's mother was told through flashbacks, instead. However, the animators changed this because they "wanted the viewers to understand the overprotective nature of Marlin" from the start.