Girl in pink-rimmed glasses sitting next to the groupies - Uncredited - DVD available from Amazon.
Dr. Horrible (Neil Patrick Harris) has a really bad couple of days fighting his nemesis, played by Nathan Fillion (Caleb in 5 episodes of BTVS). Josh Whedon produced this, along with Jed and Zach Whedon. Felicia Day (Penny) was Vi in 8 episodes of BTVS in 2003. Marti Noxon, who wrote 23 episodes of BTVS, is a newswoman. Simon Helberg (Moist) is Howard Wolowitz of The Big Bang Theory.