Trivia: Apart from Virgil Tracy, David Holliday provided the voice of just three 'guest' characters during the first series.
Trivia: At the beginning of this episode, we see Chip Morrison being put to bed by his father. Chip was last seen as Bob Williams in 'Cry Wolf', whereas his father previously appeared as Dave Clayton in the episode 'Day of Disaster'.
Trivia: This episode features the largest number of characters (in speaking roles) seen in any Thunderbirds episode or either of the feature films.
Pit of Peril - S1-E2
Trivia: Only five regular characters appear in this episode - Jeff, John, Scott, Virgil and Brains. This is the smallest number of regular characters seen in any Thunderbirds episode.
Give or Take a Million - S2-E6
Trivia: At the beginning of the episode, when Jeff and Nicky are relaxing at Tracy Island, you can see models of Thunderbirds 1, 2, 3 and 4 on the table. These models were commercially available at the time of the episode's initial broadcast and were produced by J. Rosenthal (Toys) Ltd. Thunderbird 5 is not on the table as Rosenthal's model did not look like the genuine article.
Trivia: This is the only Thunderbirds episode in which voice artist Ray Barrett does not take part.
Trivia: When Prescott is driving along in his car, he is humming the song "Marina" from "Stingray", another Gerry Anderson show.
Trivia: Throughout the second series there were three 'guest' voice artists: John Tate, Paul Maxwell and Charles Tingwell. Tate had previously voiced numerous characters in episodes during the first series such as 'Sun Probe', whilst Maxwell and Tingwell would appear in the next Gerry Anderson creation 'Captain Scarlet and The Mysterons' as the voices of Captain Grey and Dr Fawn, respectively. None of these artists were credited in the end titles.
Trivia: In Thunderbird 5, a short piece of Barry Gray's "Formula Five" track can be heard. This was composed and recorded for another Gerry Anderson creation, "Fireball XL5".
Trivia: This was the last episode in which David Holliday voiced Virgil Tracy. He was replaced by Jeremy Wilkin for the second season. Some sources say that Holliday left because he had to return to America, while others say he demanded more money.
Trivia: Although he was a regular character in the first series, the Hood does not appear in any of the six episodes in the second series.
Trivia: This is the only Thunderbirds episode to feature the entire regular cast and all five Thunderbird craft.
Trivia: In this episode, Alan Tracy's voice is completely different from the one heard for the rest of the series. In his single, short line of dialogue, Alan is voiced by Ray Barrett, as Matt Zimmerman had not been employed when voice recording commenced (although he is credited in the end titles).
Trivia: In the opening credits, you see a picture of Thunderbird 3 in the background, but Alan Tracy is not flying the craft. He in is fact flying Thunderbird 2 with the steering wheel upside down.
Trivia: When Virgil places the asleep Chip into his own bed towards the end of the episode, look behind Virgil and you can see a WASP Arrowhead Fighter Model from "Stingray" on the shelf by the window.
Trivia: The disaster of this episode is caused by a lightning strike damaging the automatic signals of a monorail train, causing it to speed towards a collapsing bridge. In 2011, a similar incident occurred in Wenzhou, China, when a lightning strike caused the railway's signals to mark a section of track as safe, despite containing a stopped train. A second train then entered and collided with the stopped vehicle, and derailed from the elevated track onto the fields below.
Trivia: The Doctor who visits Tracy Island at the end of the episode can also be seen reading a newspaper in the Departure Lounge at London International Airport.
Give or Take a Million - S2-E6
Trivia: Despite the large number of characters, Matt Zimmerman's voice is only heard once in the entire episode, when Alan says "F.A.B." during the Thunderbird 3 launch sequence.
Trivia: International Rescue's headquarters was never actually referred to as "Tracy Island" throughout the whole series.
Trivia: Jeff, Scott and Virgil are the only characters to appear in all 32 episodes of the show.
