"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.
The movie was filmed in Weirton, West Virginia because many of the main street shop fronts are leftover from when Weirton was a 1960-70s steel town.
Trope Trivia
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 Very 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.
Defictionalization: Rocket Poppeteers are available at 7-11 stores. You wouldn't know they're Super 8 tie ins unless you followed the ARG.
DVD Commentary: The commentary featuring director J. J. Abrams, director of photography Larry Fong and producer Bryan Burk has them mulling over what question to ask Steven Spielberg via email, since he never does commentaries. There's also talk of Fong's magic skills (which are demonstrated in a featurette elsewhere on the disc), and he promises to bend the silverware in the house of anyone listening to the commentary.
Promoted Fanboy: 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.
The film has Walkman cassette players just hitting the market. And because it's 1979, none of the kids have cell phones or computers to keep in touch with each other. They do have two-way radios, though.
The 3-day (minimum) turnaround time to have the film developed is a crucial Plot Point. While Super 8 film and cameras still exist and are still popularwith amateur film-makers (and some professionals), kids in an otherwise similar present-day setting would most likely use instantly-viewable digital, especially since any amateur contest would require the content to be uploaded rather than mailed on physical media.
In the very early stages of planning, the movie didn't have an alien at all. One idea that Spielberg proposed was that the kids accidentally capture a robbery in the background of their movie, and their footage is the only evidence of the crime.
Write What You Know: Apart from being an ode to early-Spielberg, the story is, in a sense, partially autobiographical with Abrams inputting his experiences of making Super 8MM films as a kid in 1979. The main kids in the film could vaguely be seen as Author Avatars.
(and some professionals), kids in an otherwise similar present-day setting would most likely use instantly-viewable digital, especially since any amateur contest would require the content to be uploaded rather than mailed on physical media.