CASTLE
ABC, 10:01 p.m. ET
In tonight’s episode, Castle (Nathan Fillion) and Beckett (Stana Katic) attend a sci-fi convention to investigate a murder. As you might expect, given Fillion’s fantasy-cred resume (his credits include Firefly, Buffy the Vampire Slayer and Dr. Horrible’s Sing-Along Blog, all for Joss Whedon), this episode is a very playful and respectful nod to fans of such shows. And yes, in-jokes abound, so be on the lookout for Extras.