Trivia / SpongeBob SquarePants: Battle for Bikini Bottom
Development Gag: Although the full Patrick's Dream level didn't make it into the full game, he still gets one where he just sort of gives you the Spatula, with him standing in a blank black room with a spotlight being the only immediate illumination. This is more likely a reference to the episode the world is based on, but it can double as Self-Deprecation.
The Other Darrin: Joe Whyte replaces Clancy Brown and Ernest Borgnine as the voice of Mr. Krabs and Mermaid Man, respectively.
What Could Have Been...: A TON, and some of it is still left in the final game itself where you have to hack it and look a bit hard for such things.
The Concept Art for the game (unlocked by paying 40,000 shiny objects to the movie theater) shows art for a proposed Robo-Squidward boss. While it was dummied out of the console games, the Game Boy Advance version did include it as a boss. It eventually become a reality, in the Truth or Square video game.
There's an unused level found in the Gamecube version, said unused level is what was supposed to be Patrick's Dream. Said level also contain several early version of in-game objects. See it here