In the future, the Earth Coalition is fighting a losing war against the Glorft Imperium, a highly advanced extraterrestrial race with an insatiable hunger for conquest who are currently trying to recover a stolen mech codenamed “Avatar Prototype”. Skilled ‘mech pilot Kiva Andru wants to send said mech, now renamed “Megas”, back to a crucial part of the conflict, but accidentally sends it too far, and Megas winds up in the hands of couch potatoes Coop and Jamie. Worse, Kiva is stuck in the past with these boneheads, not to mention a Legion of really angry Glorft intent on capturing the Megas, even if they have to resort to using the giant UMD Mech to do it.
- Originally entitled Lowbrow, the pilot episode was shown during Cartoon Network's 2002 Summer Contest to determine which cartoon would become a new Cartoon Cartoon; it was the most popular among viewers. After being delayed from its original debut in December 2003, Megas XLR finally debuted on Toonami on May 1, 2004
- The pilot episode was extended 15 minutes for the episode "Test Drive", which was aired in four separate parts at half-hour intervals. The first part was aired during the left-over "end-of-block" time from the last day of Giant Robot Week (February 28, 2003).
- The pilot episode is about seven and a half minutes long. When it was extended for the full episode Test Drive, most of the new content was added to the beginning; the pilot consists primarily of the last half of the first full episode. However, there are some differences: some lines and some scenes are changed slightly. For example, the satelite that falls on the giant Glofrt ship is labelled with the word "CCCP" over a red star instead of the POP TV logo, and Jamie doesn't describe the color of the Glorft mechs when he asks about them. Also, the art style is somewhat different. For example, in the pilot the three main character's eyes are drawn differently and do not have white around the pupils, but simply are black dots under brow ridge lines.