The series was made by Gerry Anderson, who also made "Supercar", "Fireball XL5", "Stingray", "Captain Scarlet", "Joe 90", "UFO", "The Protectors", "Space: 1999", "Terrahawks", and "Space Precinct 2040".
Inspiration for the series came from a real life disaster when a group of German miners were trapped in a mine shaft - the frantic efforts to rescue them captured the attention of Gerry and much of Europe.
Initially to be called 'International Rescue' the series was eventually named after Thunderbird Field, an airfield in the US where Gerry's brother learned to fly for the RAF during World War 2.
The script for the first episode of Thunderbirds was dictated by Gerry Anderson to his wife in four parts at their home in Portugal.
Thunderbirds was made in Slough, England.
After Lew Grade, head of ITC, viewed the pilot episode, he remarked, "That's not a television series! That's a feature film!"
Gerry Anderson later explained: "In the 1960s the buzz word was ‘fabulous’; this became shortened to fab and so we used FAB as a code meaning your message has been received and understood."
Supermarionation was a word coined by Gerry Anderson combining the words "Super", "Marionette" and "Animation".
Although never stated directly in any episode, according to Gerry Anderson this series takes place in the same "universe" as "Captain Scarlet and the Mysterons" and "Stingray." Several marionettes were modeled after the actors providing their voices.
The Tracy brothers are named after five leading US astronauts. John Glenn, Gordon Cooper, Alan Sheperd, Virgil Grissom and Scott Carpenter.
It was while the Round House (through which Thunderbird 3 would be launched) that Derek Meddings realized that the design of the building was just right for Thunderbird 5, the International Rescue space station. Unable to come up with a convincing design before now, this was the last of the five Thunderbird craft that he created. By adding aerials and transmitters to the Round House, he developed the series' most unusual and effective vehicle, although it was to play only a minor part in the finished program.
Fenella Fielding was Gerry Anderson's first choice for the voice of Lady Penelope.
Lady Penelope was once described as "an advertisement for British fashion", by The Sunday Mirror newspaper.
The only time Rolls Royce have officially sanctioned the use of their famous vertical grille and spirit of ecstasy was on Lady Penelope's pink 6-wheel Royce.
Lady Penelope's unique pink Rolls Royce is based on the same twin front-wheel-steering Bedford coach used in the escape scene of Italian Job, The (1969).
The Hood has never been referred to by any name on all but two episodes - "Martian Invasion", where he calls himself Agent 79 in his transmissions to General X, and "Edge Of Impact", where he gives his codename as "671" when he contacts General Bron. "Edge of Impact" is also the only episode in which we see the Hood acting with motives not involving International Rescue.
Issue 65 of "Thunderbirds - the Comic" revealed the Hood's real name as Belah Gaat.
Each Thunderbirds puppet only had four teeth.
In order to increase the realism of the series, close-ups of real human hands were often inserted when a character is shown about to manipulate an object (i.e. open a drawer, cock a gun).
In addition to the close-ups with human hands, three episodes pioneered a technique in which a human hand appeared in the same frame as the puppets.
There is also the appearance of a human face (or, at least part of one) when Lady Penelope looks through the entrance door of the Bank of England in the episode "Vault Of Death".
The models of the Thunderbird vehicles seen on the table in front of Jeff in the opening scene of "Give or Take a Million" were commercially available at the time of this episode's initial broadcast (25 December, 1966). They are the "Thunderbirds" model toys produced by J. Rosenthal (Toys) Ltd. Unfortunately, Rosenthal's Thunderbird 5 didn't look very much like the genuine article, so it does not appear in this scene.
Only two episodes were made in which Virgil's vehicle, Thunderbird Two, was not involved in the story's primary rescue - "Terror In New York City" and "The Imposters". "Terror In NYC"'s non-use of Thunderbird Two was forced because the episode was originally made as a half-hour show; when Sir Lew Grade of ITC demanded the series be remade in one-hour format, AP Films had writer Alan Fennell write in the subplot where Thunderbird Two is mistaken for an enemy bomber and attacked by a US warship; ironically, this helped make the episode the one most fondly remembered by original fans of the show; it also explains why this episode needed two directors (David Elliott and David Lane).
Two vocal theme songs were considered before the famous march was chosen. One of these discarded themes, "Flying High" (performed by Gary Miller), can be heard at the end of the episode "Ricochet".
Some of the guest characters were named after real people. For example: Lt. Bob Meddings (seen in the episodes "Trapped In The Sky" and "Operation Crash-dive") was named after visual effects supervisor Derek Meddings. Dr Korda (seen in the episode "Day Of Disaster") was named after Hungarian-born film producer/director Sir Alexander Korda Lady Penelope's alter ego, Wanda Lamour (from the episode "The Cham-Cham) was named after puppeteer Wanda Brown (née Webb).
The opening and closing credits of the first episode ("Trapped In The Sky") differ entirely from the rest of the series: the music arrangements are slightly different (in the closing credits, for example, the music for Thunderbird 1's first launch is used); sound effects are used in the montage (including Kyrano's scream); the Mole is not used as a standard picture in the closing credits. It is the only episode where Gerry Anderson and Sylvia Anderson are credited for writing an episode of Thunderbirds.
In the episode "Trapped In The Sky", Alan Tracy's voice is completely different from all the other episodes that he appears in. In his single short line of dialogue, he is voiced by 'Ray Barrett' , although 'Matt Zimmerman' (who did Alan's voice for the rest of the series) is credited in the closing titles. (Matt Zimmerman had not yet been asked to do Alan Tracy's voice at the time.)
In the episode "Trapped In The Sky", a short piece of Barry Gray's "Formula Five" track, composed and recorded for "Fireball XL5", can be heard on the monitors in Thunderbird 5.
The episode "Security Hazard" features extensive flashback footage from "End of the Road", "Sun Probe", "Trapped in the Sky" and "Day of Disaster" - so extensive, in fact, that it contains only around ten minutes of new material. These episodes were specifically chosen as, having originally been filmed as half-hour episodes, writer Alan Pattillo knew that the stories could be more easily condensed down to about ten minutes each.
On the Christmas episode "Give Or Take A Million", there are calendars indicating that Christmas day is a Sunday, which it actually will be in 2067, when the episode is set.
The television relay tower (featured in the episode "Edge of Impact") is seen to be owned by British Telecommunications Ltd. The use of this company name in the series pre-dated the formation of the real-life British Telecommunications plc (or BT) by nearly twenty years.
The episode "Operation Crash-Dive" was originally entitled "The Test Crew".
The music accompanying the journey of the Martian Space Probe in the episode "Day of Disaster" is entitled "The March of the Oysters". Originally composed by Barry Gary for the "Stingray" episode "Secret of the Giant Oyster", the piece is also heard in "30 Minutes After Noon", "The Impostors" and "The Cham-Cham".
In the episode "Brink of Disaster", a bogus telegram reveals the location of Lady Penelope's mansion in Foxleyheath.
In the episode "The Uninvited", the Zombites' jet fighters are adapted and re-sprayed WASP aircraft from "Stingray" (1963).
In the episode "The Mighty Atom", the teletype printout gives the date on which the atomic cloud is blown away from Melbourne as 6 October and it is then stated that the explosion at the plant took place the previous Monday. If this is 2064, the explosion therefore occurred on 29 September. It is also stated in this episode that International Rescue were not operating when the Australian plant exploded in 2064.
In the episode "Vault of Death", the City of London Heliport is partially constructed from the remains of "Stingray"'s Marineville Tower.
The launch of the Sun Probe at the start of the episode "The Perils of Penelope" is the same event that was seen in flashback at the start of the episode "Sun Probe". The events of that episode take place one week after the launch, so this episode takes place immediately before. Indeed, "The Perils of Penelope" and "Sun Probe" can be viewed as Thunderbirds' only two-part story, although they have never been broadcast as consecutive episodes.
In the episode "The Perils of Penelope", the Anderbad Express monotrain is the same model as the one seen as the Pacific-Atlantic monotrain in "Brink of Disaster" (see also the Goofs entry).
The episode "The Perils of Penelope" is the only episode in which we see Scott piloting Thunderbird 1 without his International Rescue uniform - when he returns from leave.
The episode "Danger at Ocean Deep" is the only episode in which we see John going on a rescue. He admits that he has been on just a dozen or so rescue missions, while Scott ahs been out on every single one. Therefore, unless Scott is forgetting that he didn't take an active part in the rescue in "The Perils of Penelope", the events of this episode should take place before those of both "The Perils of Penelope" and "Atlantic Inferno".
Two episodes, "The Man from MI.5" and "Attack of the Alligators!", feature the full Thunderbird 4 launch sequence shown from inside Pod 4. In other episodes featuring Thunderbird 4, we have only seen Thunderbird 4 emerging down the ramp from outside the pod door. "The Man from MI.5" is the only episode in which Thunderbird 2 gently rests the pod on the surface of the water and then rises clear of the pod with lifting jets, whereas "Attack of the Alligators" shows Thunderbird 2 lifting from the pod several minutes after landing. Normally, the pod is simply dropped on to the water.
In "The Duchess Assignment", the Duchess of Royston was based on the distinguished British stage actress Dame Edith Evans, best known for her role as Lady Bracknell in the film version of Oscar Wilde's The Importance of Being Earnest (1951). This is reinforced by Ray Barrett's marvellous voice for the character, which understandably had the rest of the cast in stitches at the recording session.
Often heralded as the series' most memorable episode, "Attack of the Alligators!" features live crocodiles in extensive footage filmed on a model set, a first for the Century 21 production team. During the episode's filming, publicity photos were taken of Lady Penelope (who did not appear in that episode) with a couple of the crocodiles.
The episode to feature the largest cast of characters (in speaking roles), seen in any single "Thunderbirds" episode or either of the feature films, was "Alias Mr. Hackenbacker", with 20 voices provided by all of the cast members from the second season (Jeremy Wilkin had replaced David Holliday as the voice of Virgil at this time), featuring Paul Maxwell as Captain Ashton, although he was not credited in the end titles.