Repeated several times in the UK, it has generated tie-ins ranging from toy cars and action figures to audio plays and novels, as well as strips in the weekly children's comic TV Century 21.

Compared to earlier Anderson productions, Captain Scarlet is widely regarded as "darker" in tone and less suited to children because of its violent content, as well as its themes of alien aggression and interplanetary war.

[E 2] They use it to wage a "war of nerves" against Earth, issuing threats against specific targets (from world leaders and military installations to whole cities and continents) and then destroying and reconstructing whatever instruments are needed (whether humans or objects) to carry out their plans.

[E 1][15] After being shot by Captain Blue and falling to its death from the top of a tower, the reconstruction returns to life with the consciousness of the original Scarlet restored, and is thereafter free of Mysteron control.

[N 6][E 1] With his new Mysteron body, Scarlet possesses two extraordinary abilities: he can sense other reconstructions nearby; and if he is injured or killed, his retrometabolism restores him to full health, making him virtually "indestructible".

[17] Having overseen APF's work since the making of Supercar in 1960, Grade was keen for Supermarionation to penetrate the lucrative American market and believed that a new concept would stand a better chance of landing a network sale than a second series of Thunderbirds.

This, coupled with contemporary theories about the possibility of life on Mars, led to the idea of an interplanetary war between Earth and its neighbour and a security organisation being called on to defend humanity.

For example, he remembered that during the Battle of Britain, RAF pilots had struggled to counter German attacks quickly, because having to take off from the ground meant that it took a long time to intercept the enemy.

[41] In Tingwell and Maxwell's absence, Fawn and Grey's roles were reduced to a handful of non-speaking appearances, though guest characters voiced by the two actors can be heard in flashbacks to earlier episodes.

On all the Anderson series prior to Captain Scarlet, the solenoid that powered the automatic mouth movements had been housed in the cranium, which caused the puppets' heads to appear disproportionately large compared to the rest of their bodies.

[9] Before the pre-production of Captain Scarlet, producers Reg Hill and John Read created a new type of puppet with the solenoid built into the chest, enabling the heads to be reduced to a realistic size.

"[18] Sculptor John Brown remembered putting the prototype next to the Lady Penelope puppet from Thunderbirds and gauging his colleagues' reactions: "When they saw it, some people were horrified by the difference.

The closing titles were originally intended to show images of printed circuit boards and other electronic components to reflect the early concept of Scarlet being a "mechanical man".

Although Lane, Brian Burgess and Desmond Saunders reprised directorial duties for at least one episode each, the Andersons were forced to promote some of the junior production personnel to replace the outgoing directors.

[112] In their notes on the CD release, Ralph Titterton and Tim Mallett write that the Captain Scarlet soundtrack has a "military feel" that favours percussion, brass and wind instruments, in contrast with the full orchestral sound of Thunderbirds.

[113] Gray preferred traditional instruments for much of the action, limiting electronic music to scenes set in outer space and an echoing four-note motif that serves to identify the Mysterons.

[117] In his BBC Online review, Peter Marsh suggests that the grimness of the music reflects the series' use of realistic puppets and its presentation of death, as well as its alien villains and lack of humour.

He comments that "dissonant vibraphone chords shimmer under hovering, tremulous strings contrasted with urgent, militaristic drums and pulsing brass—driving the action ever onto its climax (and, no doubt, a big explosion).

[128] Following the September 11 attacks, the episode order was changed: "Winged Assassin" (in which the Mysterons destroy an airliner) and "Big Ben Strikes Again" (in which they hi-jack a nuclear device), were postponed due to perceived similarities between the plots and real-world events.

[95] In 2017, the series' 50th anniversary year, UK company Network Distributing announced that it was releasing Captain Scarlet on Blu-ray Disc with all episodes remastered in high definition using the original 35 mm film negatives.

[81] For Jim Sangster and Paul Condon, the optimism of Stingray and Thunderbirds is noticeably absent, with heroism and unqualified victories replaced by desperate games of "damage limitation" as Scarlet and Spectrum rush to counter every Mysteron move, sometimes unsuccessfully.

[171] Nicholas J. Cull writes that the "war of nerves" between Earth and Mars echoed real-world geopolitical conflict, while the "enemy within" scenario of Martians taking over humans was derived from films like Invasion of the Body Snatchers (1956).

[175][176] According to Bould, it is one of several Anderson productions that depict a "utopian future benefiting from world government, high technology, ethnic diversity, and a generally positive sense of Americanisation.

[11][179] In a 1986 interview, script editor Tony Barwick described Captain Scarlet as "hard-nosed stuff" that lacked humour, adding: "It was all for the American market and to that extent there was no deep characterisation.

[180] In contrast, Jeff Evans considers the characters "more detailed" than before, arguing that Captain Scarlet was the first Anderson production to give them "private lives and real identities".

Comparing it to Thunderbirds, John Peel summarises Captain Scarlet as "better puppets, bigger action and a huge step backwards in stories", arguing that the superior special effects were to the detriment of the writing.

"[11] Peel also finds fault with Scarlet himself, arguing that an "indestructible" hero who risks his safety to thwart enemies was a poor role model for impressionable children and made the episode endings predictable.

[189] For Sellers, the inclusion of Green and especially Melody Angel, a black female character, shows that Captain Scarlet was "actually ahead of its time in respect to race relations".

[227][228] In 1999, Anderson supervised the production of a computer-animated test film, Captain Scarlet and the Return of the Mysterons, to explore the possibility of updating some of his 1960s puppet series for a 21st-century audience.

[229] Produced by the Moving Picture Company under the working title Captain Scarlet – The New Millennium, the four-minute film was made using a combination of Maya animation software and motion capture technology.