I've heard a bit about Castle. Haven't watched it, and I'm still probably not about to start, but this particular bit is just hysterical. Because, really, Castle does need to dress up for Halloween, right? And he would have this costume handy. *giggle* Thanks to
lechatnomade for the link.
Castle's Halloween Costume Watch a bit beyond the opening sequence to enjoy a couple of other pop cultural references, too, one from the Whedonverse and the other not.