The entire interior of Serenity, and some of the exterior, was built full-scale and almost completely contiguous. It was split across two sound stages: one for the upper deck and one for the lower deck, shuttle docks, and hold.
Joss Whedon intended the show to have run for seven seasons. While there were low ratings at first, the real reason it was cancelled was that the FOX executives thought it was too dark. Joss Whedon and the cast refused to change the storyline, so FOX Network canceled it with only 11 episodes out of 14 airing on the network. Prior to its cancellation fans formed a Firefly Immediate Assistance campaign which involves sending in postcards to the FOX Network to support the production of the show. After that didn't work, the campaign worked on getting another network such as UPN to pick up the series for a second season. The campaign ended up being unsuccessful in securing the continuation of the show.
The Alliance's full title is the "Anglo-Sino Alliance." Joss Whedon intended for it to be the merger of USA and China, the last of the world's superpowers. That's why many characters sometimes speak Chinese. The Alliance flag, seen in the original pilot, is a blending of the US and Chinese flags.
Fox originally aired the episodes out of chronological order. The proper chronological episode order is as follows:"Serenity", "The Train Job", "Bushwhacked", "Shindig", "Safe", "Our Mrs. Reynolds", "Jaynestown", "Out of Gas", "Ariel", "War Stories", "Trash", "The Message", "Heart of Gold", and "Objects in Space".
Every scene in space is shot without sound effects of the ship moving, precisely as it would be in real life; no air, no sound. Of course, that doesn't cover the background music played during those scenes.
The cast had a running gag where they would yell Summer Glau's name whenever they flubbed a line or messed up. It began after she forgot her line at the end of a particularly difficult scene. The gag continued through the filming of Serenity (2005).
As with Star Trek (1966), the first pilot was rejected, forcing the preparation of a new one, "The Train Job." The original pilot, "Serenity" (which introduced the characters and their story arcs) was the final episode aired in the show's original run.
During the DVD commentary, it is mentioned that there was a subplot for Inara that was never developed but that was foreshadowed with a number of shots and/or lines during the series. At a 2008 Dragoncon panel, Morena Baccarin confirmed the long-standing rumor that that subplot would have involved Inara having a terminal illness.
Serenity's engine room includes the center console from a Boeing 737, complete with throttles, fuel cutoffs, spoiler and flap levers, and pitch trim wheels. It's frequently seen standing on the floor between the cot and the engine.
Although it has been long known that the relationships between Firefly's showrunners and FOX, the network on which it aired, were fraught, in 2014, Business Insider and Amy Pascale's biography of Joss Whedon both provided some never-before-published further details about how FOX executives completely misunderstood the show's aims. Some examples include: FOX at first refused to pick up the show because they didn't like the fact that the characters Wash and Zoe were married (thus scuttling any chance for romance between Zoe and Mal); they relented when Joss Whedon insisted. The network constantly asked for the show to be less dark, but also wanted Mal to shoot more people. Pascale also recounts how completely FOX misrepresented the show in its ad campaign--instead of advertising it as either a science fiction or a western show, it instead made ads implying that it was an offbeat comedy, scored to the wacky 1997 Smashmouth song "Walking on the Sun."
Nearly all of the main cast members have appeared as villains in other Joss Whedon projects. Nathan Fillion appeared in the seventh season of Buffy the Vampire Slayer (1997) as Caleb. Gina Torres appeared in the fourth season of Angel (1999) as Jasmine. Adam Baldwin also appeared in "Angel" (1999), but in the fifth season as Marcus Hamilton. After "Firefly" (2003), Summer Glau and Alan Tudyk appeared in Dollhouse (2009) as Bennett Halverson and Alpha, respectively. Sean Maher played Don John in Whedon's movie of Much Ado About Nothing.
According to Amy Pascale's 2014 biography of Joss Whedon, Whedon proposed a Firefly plotline in which Inara injected herself with a prophylactic solution - not a birth control but a serum that would poison anyone who raped her. Whedon's idea was that Inara would then be kidnapped and gang-raped, but that the rapes would take place offscreen, and the only sign of them would be a pile of her rapists later found dead. This plotline was nixed by the network and no version of it ever appeared on he show.
Some of the weapons used in the series were contemporary with the time of production and chosen based on their somewhat futuristic look. No modifications were made by the prop department to either disguise them or make them look more futuristic. Alliance soldiers are seen carrying British L85A2 rifles and Heckler & Koch MP5s, both in variant models. The Browncoats are seen using Heckler & Koch G36 rifles.
Morena Baccarin's character Inara is named for a goddess worshiped by the Hittite (Hurrian) Empire of what is now Turkey, circa 1800-1200 BC. Inara was the goddess of the wild animals of the steppe and daughter of the Storm-god Teshub/Tarhunt. She is analogous to the Greek Artemis and the Roman Diana.
In several episodes (for example Firefly: The Train Job (2002), Jayne wears a German police jacket, from the state of Rhineland-Palatinate (German: Rheinland-Pfalz). The badge on the right sleeve has the word "Polizei" (German for police) on the top and the emblem of Rhineland-Palatinate underneath.
The pistol-sized lever action gun Zoe wears on her hip and sometimes uses is called a Mare's Leg. It is a cut down Model 1892 Winchester, the same gun used by Steve McQueen in the tv series _"Wanted: Dead or Alive" (1959)_.
Many of the names of off-camera and minor characters are drawn from the ranks of science fiction writers. Notably, Bester (Alfred Bester) as the original mechanic of Serenity and Brennert (Alan Brennert) and Ellison (Harlan Ellison).
In September 2012, the New York Times reported on an American couple (Amber Balmer and Trey Memmott) who were such big "Firefly" fans that they not only incorporated references to the show into their wedding ceremony, but they also both changed their last names to "Reynolds" in tribute to the character of Capt. Malcolm Reynolds. After the wedding officiant introduced the couple as "Mr. and Mrs. Reynolds," she proclaimed, "No power in the verse can stop them!"
Both Sean Maher (Simon) and Summer Glau (River) have appeared in Arrow (2012), as Mark Scheffer/Shrapnel and Isabel Rochev/Ravenger respectively. Though they didn't share any episodes or scenes together.
Media coverage of Joss Whedon's shows often mention his practice of gathering cast members and other friends at his house to hold informal readings of Shakespeare's plays. Whedon's enthusiasm for Shakespeare's plays is reflected in a number of references throughout Firefly. These include the names of several planets visited by the Firefly crew (Ariel and Miranda are both characters from The Tempest) and plot devices (in both "Ariel" and "The Message," different characters take a drug that slows their physiological functions enough to make them appear to be dead; this completely fictional drug is a major plot device from Romeo and Juliet, which Shakespeare wrote in the 1590s). Whedon's Shakespeare readings eventually developed into a feature film version of Much Ado About Nothing (released in 2012), which also starred Firefly regulars Nathan Fillion and Sean Maher.
Summer Glau later went on to star in another science fiction TV series "Terminator: The Sarah Connor Chronicles", which is based on the films starring Arnold Schwarzenegger. In that series, Glau starred as Cameron Phillips, a mysterious teenage girl who is revealed to be a female Cyborg from a post-apocalyptic future. The character of Cameron Phillips had been written with Summer Glau in mind for the role and Glau got the part partly due to the strength of her fight scenes in the film "Serenity", which is a sequel to "Firefly".
Objects in Space (#1.10), which was the final episode of the series, saw bounty hunter Jubal Early sneak aboard "Serenity" to capture River Tam. In the final episode of the British series "Blake's 7" Blake (#4.13) The Scorpio crew discover their former leader Roj Blake is now a bounty hunter. Paul Darrow, who played Kerr Avon in that series, was a fan of the film "Serenity", which is based on this series.
In the 1970s and early 1980s, Ron Glass was a cast member of the sitcom Barney Miller (1974), which was set at the 12th precinct of the New York Police Department. While it was likely just a coincidence, the NYPD's 12th precinct was also the setting of Nathan Fillion's series Castle (2009).