In Halloween episode S02E06, Castle and his daughter have a Firefly/Serenity reference. : r/firefly
18 Times Actors Re-Created Iconic TV And Movie Costumes
Castle" Vampire Weekend (TV Episode 2009) - IMDb
How to Pull Off Insanely Creative Costumes | Men's Health
Nathan Fillion Reflects on FIREFLY, CASTLE, and THE ROOKIE with Alan Tudyk, Gina Torres, Joss Whedon, and More — GeekTyrant
Watch out for naked nannies as Fillion actor hits Supanova | The Courier Mail
Internet-savvy 'Firefly' fans fly back into the fight - CNN.com
Rick Castle dressed as Malcolm Reynolds. (Oh, I love the jokes they keep dropping into Castle about Firefly.) | Mal reynolds, Geek humor, Richard castle