Actor Allusion: In the 1980s TV series V, one of the important characters is a battle-hardened Resistance leader fighting against the Visitors, a group of extraterrestrial lizard-people. In this movie, the main villain is a psychotic human warrior fighting with a group of lizard-men as their leader (see below). Both characters are named Tyler, and both roles are played by Michael Ironside.
The Danza: Julie is voiced by Penthouse Pet and B-movie queen Julie Strain. The character is even designed to look like her.
Thank Nepotism for that - Strain was married to Heavy Metal's editor-in-chief Kevin Eastman (he of the Teenage Mutant Ninja Turtles, and a co-writer of the graphic novel the film is based on) at the time.
What Could Have Been: The plot was meant to be connected and more complex than an anthology, but due to the release date being bumped up and a rushed production, the animation had to be done by several animation houses, including CinéGroup and Atkinson Film-Arts. Some of the ideas were Hanover Fiste showing up in So Beautiful, So Dangerous, appearing on Zeke and Edsel's ship, saying "Sternn will go free!" and a sequence linking Sternn and B-17 called Neverwhereland, wherein the Loc-Nar lands on a planet and affecting its development.
Kyle Gass had revealed that the director of Kung Fu Panda had approached Tenacious D with an idea for a remake of Heavy Metal. The band was to appear in it as a duo of alien stoners, and they even composed the song "Deth Starr" for the film. Unfortunately, though, the idea never came to pass for fear that an R-rated cartoon would not sell well, so the band ended up releasing the song years later on their album Rize of the Fenix.