This Dr. Horrible's Sing-A-Long Blog photo contains
boater, leghorn, panama, panama hat, sailor, skimmer, straw hat, fedora, felt hat, homburg, stetson, trilby, and snap brim hat.
There might also be
cavalier hat and slouch hat.
Dr. Blog-Bot of DoctorHorrible.net, a fan site dedicated to Dr. Horrible's Sing-Along Blog says that Joss Whedon has promised very special DVD extras including a "musical commentary."
"Dr. Blog-Bot of DoctorHorrible.net, a fan site dedicated to Dr. Horrible's Sing-Along Blog discusses how fans reacted to issues during the Joss Whedon web series debut and how the faithful have taken to it since."