Rick McCallum, producer of the Star Wars prequels, recently revealed the staggering cost behind the cancelled Star Wars: Underworld series: a hefty $40 million per episode. This exorbitant budget, exceeding even the cost of the films themselves, ultimately led to its demise. McCallum explained on the Young Indy Chronicles podcast that the ambitious scale of each episode, even with the technology available at the time, made it impossible to reduce costs below this figure. He described the project's cancellation as "one of the great disappointments of our lives."

With 60 third-draft scripts penned by "the most wonderful writers in the world," showcasing a "sexy, violent, dark, challenging, complicated, and wonderful" side of the Star Wars universe, the budget proved insurmountable. The estimated cost easily surpasses $1 billion, a sum even George Lucas couldn't secure in the early 2000s. McCallum suggests that the series' expansive vision would have drastically altered the Star Wars landscape, potentially preventing Disney's acquisition of the franchise. The project was ultimately shelved after Disney's acquisition of Lucasfilm.

While McCallum remained tight-lipped on specific plot details, fan speculation centers on the series bridging the gap between Revenge of the Sith and A New Hope. Previous statements indicate a new cast of characters, a significant expansion of the Star Wars universe, and a target audience of adults, rather than children and teens.

First unveiled at Star Wars Celebration in 2005, and with test footage leaked in 2020, Star Wars: Underworld remains a tantalizing "what if?" Sadly, it appears unlikely to ever see the light of day.