"The Case" was filmed by the kid actors themselves alongside the main film.
The kid actors got to choose their characters' bikes and Abrams let them keep them after the shooting was over.
In addition to being on-camera, Bruce Greenwood also served as the Alien's motion capture actor in early tests for the thing. Before the producers decided to make it less humanoid in movement.
Beam Me Up, Scotty!: The most commonly used poster for this film (and, in fact, the one used on the movie's page on this wiki) was actually fan-made. The official poster is much more minimalistic, merely showing the town's silhouette over a blue backdrop. This is probably why the fan-made one is more popular.
J. J. Abrams' "good-luck charm" Greg Grunberg makes an extremely fleeting appearance on a TV screen at one point. Bruce Greenwood makes a cameo too as the alien, as does frequent Abrams collaborator and composer Michael Giacchino, although his face is certainly less well-known.
Promoted Fan Boy: J. J. Abrams had grown up making his own movies and being a huge fan of Steven Spielberg's early work. After being featured in a newspaper article about a Super 8 film festival, Abrams was contacted by Spielberg's assistant and was given the job of editing and restoring his idol's own 8 mm movies. Abrams got to work directly with Spielberg on this film, which was the former's love letter to the latter and which was produced by Spielberg himself.