Gerry Anderson's first live-action TV series, after a number of shows produced in the "Supermarionation" process. Star Ed Bishop provided voices for one of these shows, _Captain Scarlet and the Mysterons (1967)_
In this series, the term "U.F.O." is usually not "spelled out". Most often, it is pronounced as a word: "you-foh." Only automated systems like the voice of the computer on the interlink satellite pronounce it "you-eff-oh".
Female moonbase personnel wore purple, pink and blue wigs because Gerry Anderson thought the color looked the best under the set's lights.
Gerry Anderson intended the second season of the series to focus on alien attempts to destroy the Moon. When "UFO" was cancelled, Anderson developed this idea into Space: 1999 (UK).
Initially Ed Bishop's hair was bleached for the series. As time wore on they decided to switch to a blonde wig instead to avoid damaging his hair with repeated bleaching. Bishop used to own this wig and would bring it with him to sci-fi conventions.
The series was filmed at two separate studios due to the untimely closure of MGM's Borehamwood Studios. Pinewood Studios became the final studio after a six month wait for availability. Because of this, many of the non-contractually obligated actors left to pursue other projects, making recasting a necessity for some roles.
In the UK, people drive on the left side of the road and steering wheels are on the right side of the vehicle. However, in UFO's version of 1980s Britain, both of these have been reversed. The show's creators were simply going along with what was being predicted at the time, which was that the UK would switch its driving system sometime in the near future. That change never happened.
On December 31, 1994 the video game company Microprose released a game called "UFO: Enemy Unknown" based on this TV series.
The name of the planet that the aliens hailed from is never mentioned.
Henderson's middle initial is revealed to be "L".
Keith Alexander is dubbed by Robert Rietty.
The date the shooting supposedly took place, April 12, 1981, was the 20th anniversary of the flight of Yuri Gagarin. It is also the date of the first launch of the Space Shuttle, a little over 10 years after the time this aired.
The character of Blind actor Sir Esmond played by Ronald Culver was based on real life blind actor Esmond Knight.
When the the character of Colonel Lake was male Gary Raymond was the front runner but it was decided to make Colonel Lake a woman and so Wanda Ventham won the role.
Although aired near to the end of the series' original run, this was the second episode made and should be viewed as such.