There’s something endlessly hilarious to me about so many Whedonites and genre nerds tuning in week after week for Castle, a show that looks to be like the kind of generic crime drama that, had it aired in the 70s, would have been stripped in reruns between Quincy, MD and Columbo, simply because it stars Nathan Fillion. Last night the show threw those fans a bone by having Fillion’s character briefly get into costume as a familiar hero, and then offered a touch of light comedy commentary.