Trivia: After the series became a major success upon release in 2008, director Joss Whedon teased that he would be doing a sort-of "sequel" at some point in the future. At one point, an outline and a number of songs for the sequel were written, though due to other obligations, Whedon had to push back production. As of 2018, the long-rumored sequel has yet to materialize, though everyone involved has continued to hint that a follow-up may still happen eventually.