Rick McCallum, producer of the Star Wars prequels, recently revealed the staggering cost behind the cancelled Star Wars: Underworld series: a whopping $40 million per episode. This exorbitant budget, driven by the ambitious scale of each episode surpassing that of the films themselves, ultimately led to its demise. "The problem was that each episode was bigger than the films," McCallum explained on the Young Indy Chronicles podcast. He lamented the project's failure 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. Even at the early 2000s, the potential cost—easily exceeding $1 billion—was beyond reach, even for George Lucas. McCallum suggested that the series' immense scope would have drastically altered the Star Wars landscape, potentially impacting Disney's subsequent acquisition of the franchise. Disney's takeover and Lucas' departure ultimately sealed the series' fate.

While McCallum remained tight-lipped on plot specifics, fan speculation centers on the series bridging the gap between Revenge of the Sith and A New Hope. Previous statements indicated a new cast, significant universe expansion, and an adult-oriented target audience, distinct from the teen and child-focused content prevalent at the time.

First unveiled at Star Wars Celebration in 2005, and with leaked test footage surfacing in 2020, Star Wars: Underworld remains a tantalizing "what if?" Sadly, it appears this ambitious project will likely remain unrealized.