Bushwhacked - S1-E2
Corrected entry: When discussing the Reavers, Shepherd Book has a cord sticking out between the back of his shirt and the back of his neck. It seems to be an audio cord but could be a part of his pony tail as well. Whatever it is, it's definitely out of place during the shot. (00:22:00)
Correction: Look closely when Mal responds to Book's philosophy of "a power greater than men, a power that heals". The cord is used to tie his hair back, it isn't an audio cord.
THGhost