When Shepherd Book tells everyone about the electrical nets, Jayne says, "One day you're gonna tell us all how a preacher knows so damn much about crime." Shepherd then turns to leave. But in the immediate close up of him and Mal, he turns to leave again.
Nathan Fillion, Gina Torres, Adam Baldwin, and Alan Tudyk all later played villains on Joss Whedon's other Mutant Enemy productions: Fillion appeared as Caleb in the final five episodes of "Buffy the Vampire Slayer," while Torres played Jasmine in season four of "Angel" and Baldwin played Marcus Hamilton in season five. Tudyk played Alpha in "Dollhouse".