All-Star Cast: We have Debi Derryberry, Rob Paulsen, Jeff Garcia, Patrick Stewart, Meghan Cavanagh, Mark DeCarlo, and Carolyn Lawrence playing many of the lead characters, with the supporting cast including Carlos Alazraqui, Kimberley Brooks, Frank Welker, and Laraine Newman, among others. Quite a crew.
Keep Circulating the Tapes: On May 19th, 2007 Nickelodeon premiered a TV Special called GENIUS, SHEENIUS, OR INBETWEENIUS. This special was the movie with in-character commentary done by the silhouettes of Jimmy, Carl, and Sheen in the style of Mystery Science Theater 3000 (It was also the last time Debi would voice Jimmy as the series had ended by that point, so it was a Bookend in a way as well). It aired with quite a bit of promotional advertising and fan fare, but was never shown again, and couldn't even be found online until recently.
Missing Trailer Scene: Pretty much everything in the teaser. Justified, as a lot of it is very early test footage. Most of the scenes got recycled for smaller shorts that premiered during commercial breaks on Nickelodeon around the time the film came out.
Unintentional Period Piece: While the aesthetic for Retroville is, as the name implies, 1950s Ray Gun Gothic, the soundtrack is a nice little time capsule of early 2000s teen pop. Aaron Carter, whose career has since completely dried up, has no fewer than three songs on it!
The film originally acted as the pilot episode (titled Runaway Rocketboy) for what would eventually become The Adventures of Jimmy Neutron: Boy Genius. As mentioned on the film's main page, Nickelodeon was so impressed with the pilot, that they funded a whole feature length film based on it. In a sense, the film itself acts as the pilot for the animated series. Not many cartoonists can brag about something like that, you know.
The original script for Runaway Rocketboy was planned as an independent live-action short, but John A. Davis could only get funding for it if it was educational. He dug out the script a few years later when his company DNA Productions was getting started.
Kevin Michael Richardson was going to voice either King Goobot or a general where they retrieve the toaster. The footage can be found in the trailer.
If you go through every pre-release media (possibly including trailers), you'll notice that they are from a earlier version of the film.
The most notable is the fact that Jimmy and his friends were all going to go to Retroville and rescue their parents is separate rockets rather than just Jimmy and Carl.
Easter Egg: One sound clip in the game files sounds like a brief segment from Carmina Burana, followed by some loud, high-pitched, and mostly incomprehensible noises that vaguely resemble speech. If you slow it down 50% and listen carefully, it's somewhat discernible. Here's a guess at what might be said:
Voice 1: "(Conti)nue the search. Please target the house and retrieve them there with the small wooden objects."
Voice 2: "Order our flank and to target that building and teleport him to me, at once!"
Whether this is an actual Easter Egg, an error in exporting the sound from the game files, or merely the developers being silly is unknown.
What Could Have Been: This pre-release screenshot◊ looks very different from the released version. Most notable are Jimmy's different appearance, Goddard having his own neutron energy meter, a Yokian guard and ship roaming the school grounds, and the school grounds laid out differently.