Zim's eyes in the pilot are light pink, rather then their usual ruby color.
This test pilot was not aired when the series original run on television. It was first released to the public on the Volume One DVD set on May 11, 2004. It aired on television years later on Nicktoons on December 24, 2011, as a special presentation.
Mark Hamill was originally the first choice to voice ZiM in the pilot, but it didn't sound right to Vasquez. Fortunately, the pilot then featured Futurama's Billy West as the voice of the title character, but due to doing voice over work on Futurama at the time, he was replaced with Richard Steven Horvitz.
The pilot originally began production in 1998, and was finished in 1999. Despite being produced by Nickelodeon Animation Studios, the Nicktoons closing logo was not shown in the DVD release.