The producers were requested to specifically not cast the Sinestro Corps, the classic archenemies of the Green Lanterns, but instead showcase other Corps within the show. The show featured Red Lanterns, Star Sapphires, Blue Lanterns, the Orange Lantern and homaged the Black Lanterns; the only other Lantern colors they did not feature are the Indigo Tribe and the White Lanterns.
The series producer Bruce Timm was originally reluctant to use CG animation instead of traditional animation, but eventually came around making this the first CG animated television series by Bruce Timm and the first series featuring Green Lantern to be rendered using CG animation.
The show runners did have to tone down the designs for one of the Star Sapphires, but that was long before anyone knew what time the show would air. Broadcast Standard & Practices thought she was too naked.
Josh Keaton, the voice actor for Green Lantern/Hal Jordan, was virtually unfamiliar with Green Lantern and read Green Lantern: Rebirth to get an insight into Hal's backstory and motivations and based his performance on "Green Lantern: Secret Origin" after reading that story arc.
The writers and producers were asked not to use Sinestro very much at the time they were developing the show, because at that time his destiny wasn't completely decided in how DC wanted to play him in the future.