- The writers of Castle are not shy about appealing to fans of Firefly. On top of the fact that Castle wears brown coats frequently, more direct references include:
Alexis: didn't you wear that like five years ago?Castle: So?Alexis: So, don't you think you should move on?Castle: I like it. (a reference to his own continuing commitment to the fandom. Real-life Still Wearing the Old Colors)
- In the Halloween episode "Vampire Weekend," Castle dresses as a "space cowboy" (together with musical signature and guns).
- Towards the end of the episode, Ryan compliments him on throwing such a good "shindig," which is also the name of a Firefly episode.
- In "Boom!," Castle shoots the baddie's hand to get him to drop his weapon, and Beckett gives him a "Hell of a shot, Castle," Castle replies, "I was aiming for his head."
- In "Close Encounters of the Murderous Kind", he speaks Mandarin to a couple of Chinese workers. Beckett asks him "Summer abroad?" and he replied, "No, a TV show I used to love."
- Castle describes his first ex-wife as a "special brand of Hell." Note that the Firefly episode this quote is referencing also has a manipulative, sexy redheaded temptress.
- Likely unintentional, but the scene in "Punked" where Castle meets Alexis's boyfriend, Ashley, ends with him offhandedly toying with the old-timey gun in his hand, no doubt something he picked up from some other show he did. Shortly thereafter, another slight Firefly reference surfaces when Castle tells Beckett about Ashley, "who has a girl's name, by the way,"
- "Setup": Talking to him about the "Oasis of Serenity" spa, Martha asks, "You've never heard of the Serenity?" It is followed by a close up on Castle casting an Aside Glance which turns out to be him looking at Alexis.
- When posing as a drug buyer, Beckett says she wants to feel "shiny."
- In "The Blue Butterfly", a 1940's gun moll is named Vera.
- "Headhunters", which reunites Nathan Fillion and Adam Baldwin, surprisingly has no direct references to Firefly with the exception of Baldwin's character basically being Jayne-as-a-NYPD-detective. However, fans' ears will perk up when they see a scene revolving around a brown coat and Baldwin talking about watching your partner's back. Also, Castle's first scene has him playing with toy dolls à la Wash's introductory scene. And Slaughter says that Castle has a "very fine coat", which could be referencing Badger's "very fine hat".
- In "Murder, He Wrote," Castle says that the backyard is his favorite part of his house in the Hamptons because of "the serenity".
- Yet another episode has the protagonists donning medical gloves while checking out a crime scene. Castle is visibly amused by the idea of wearing blue gloves — and copies River Tam's 'two by two' gesture.
- "The Final Frontier" is absolutely full of Firefly references. There are three in the opening scene alone: When Castle hears they'll be investigating a crime at the sci-fi convention, he says "Shiny," when listing off his favorite sci-fi series...well, the producers can't use the title, but he does mention "that Joss Whedon show," and finally there's a lot of talk about how the fictional show Nebula-9 has a devoted fanbase despite only running for twelve episodes and being cancelled a decade ago (Guess whose ten-year anniversary was coming up that weekend?). There are even more references scattered throughout the episodeon Nebula-9, the captain's name is Max Renard (sounds quite similar to Mal Reynolds), there's an alien race called Kreavers which will eat your face off, and in Beckett and Castle's pool of suspects, one has the last name Frye and another is named Simon. The writers clearly had a field day with this one.
- The Nikki Heat Book Series also has several references to Firefly, including a suspect talent manager telling Rook he resembles Malcolm Reynolds, as well as two detective partners named 'Malcolm' and 'Reynolds' in Heat Rises and Frozen Heat, leading to Rook to state in the latter, "I can't quite put my finger on it, but there's something I like about Malcolm and Reynolds".
- "Vampire Weekend," the episode alone is comprised of lots of Actor Allusions:
- Beckett indicate that she's a fan of the works of Frank Miller (Stana Katic had a role in Frank Miller's adaptation of The Spirit).
- Castle name-checks Buffy, where Fillion guested as the last Dragon.
- The costume party gets actors to dress up in former roles. In particular, Esposito dresses as a US Marine (referencing Jon Huertas as Sgt. Espera in Generation Killnote , while Ryan dresses up as a doctor (referencing Seamus Dever's role in General Hospital).
- In "When the Bough Breaks," Castle gets a chance to write about a certain British spy. Stana Katic was in Quantum of Solace, playing the Canadian woman in the scene in Russia at the end.
- In "Deep In Death", Beckett mimics a Russian accent to get past a couple of guards to save Castle. Stana Katic actually speaks four separate Slavic languages fluently, making this a Katic reference as well.
- In "Tick, Tick, Tick..." Martha is watching an old episode of The Incredible Hulk. Specifically, she's watching the pilot episode, which features Susan Sullivan...who plays Martha on Castle. Since Martha's an actress, it's explained as her watching her own old stuff.
- Castle jokes about his sexless relationship with his last wife to Jordan Shaw. Nathan Fillion and Dana Delaney once played husband and wife on Desperate Housewives.
- In "Wrapped Up in Death", Erick Avari plays a superstitious museum curator involved with a Mummy. In the same episode, Castles pants end up getting ripped, which may be a reference to Captain Mal's nickname "Captain Tightpants."
- In "Food to Die For", Castle gets some liquid nitrogen and suggests he build a weapon... to change the weather. The scene is very reminiscent of another thing Nathan Fillion has been in. In the same scene, he also flubs an evil laugh.
- Mark Fallon's suit, hair, and American flag lapel pin make him pretty much indistinguishable from Nathan Petrelli. To be fair, politicians and federal agents have more or less the exact same dress code. And hair cut. And flag pin. And chiseled jaw line (they wish).
- In "One Life To Lose," there are several mentions of General Hospital, which Seamus Dever used to be on. The title references One Life to Live, which Nathan Fillion used to be on.
- In "Eye of the Beholder" an informant calls Castle "Jason Bateman", and Castle says that the resemblance got him out of a traffic ticket one time — which is a story that Fillion has told several times. This also occurs in Best in Show with the paparazzi believing it.
- The killer in "Demons" is a demon indeed.
- Tom Dempsey (and his grandson) is The fallen angel, but he also moonlights as a mysterious island guardian.
- An investigator played by Carlos Bernard offhandedly mentions a list of agencies interested in the victim of "The Human Factor," including the New York Police Department Counter-Terrorist Unit. Towards the end of the episode he also mentions coming from Chicago, which he has in common with both Carlos Bernard and Tony Almeida.
- On the Halloween 2009 episode references Buffy the Vampire Slayer, on which Nathan Fillion appeared in Season 7. Castle comments upon finding the murder victim du jour with a stake through his heart:Castle: Looks like Buffy's visited the Big Apple.
- "A Deadly Game" guest stars Mitch Pileggi of The X-Files fame as a spy involved in a secret conspiracy except he's actually just LARP-ing, and pulls out the old Skinner classic of throwing someone (i.e. Castle) against a wall to menace them into doing what he says.
- In "The Squab and the Quail", Ioan Gruffudd plays a genius-level inventor, billionaire and all-round innovator. You might say he's a Mr. Fantastic, even.
- In the season 6 episode "In The Belly of the Beast" Beckett is forced to go undercover as an assassin. This is rather similar to one of Stana Katic's early acting roles in the movie Stiletto. Though this film is not exactly something she's proud of.
- In addition to being filled with Firefly references, "The Final Frontier" was also lousy with Star Trek references, as well. Starting with the fact that the episode was directed by Jonathan Frakes (who makes a cameo in the episode), Captain Max Reynard acting quite a bit like one William Shatner, and a sci-fi replica seller is played by Quark (out of Ferengi makeup, of course).
Actor Allusion / Castle