* The series has the unusual distinction of being mentioned in a U.S. Supreme Court decision, in the case of ''Hudson v. [=McMillian=]'', 503 U.S. 1 (1992), where Justice Clarence Thomas quoted from an earlier Seventh Circuit decision., ''Williams v. Boles'' by Judge Frank Easterbrook (the context was less than complimentary, however, as watching reruns of the show was mentioned as a form of torture). See [[http://en.wikipedia.org/wiki/Hudson_v._McMillian this article]] on TheOtherWiki.

* CreatorCouple: Gerry and Sylvia Anderson.
* ExecutiveMeddling:
** Anderson wanted to make a fairly straight space-colony science-fiction show. Then the executives asked if there would ever be stories set on Earth. He said probably. They said they weren't willing to allow that. Hence the idiotic setup with the moon being blown out of orbit.
** Anderson was originally planning to make a second season of ''UFO'', entitled ''UFO:1999'', set 19 years after the original series. The idea was that the fight against the aliens had intensified and the defensive moonbase had been greatly expanded. Falling ratings for ''UFO'' in the States led to ITC cancelling the second season during pre-production, at which point Anderson suggested salvaging something by redeveloping it as an entirely different series. However, it's certainly correct that ITC insisted that some means should be contrived by which no stories could be set on Earth.
** Meddling with the writing was also the reason that Barry Morse quit after the first season, and the second became more action-oriented.
* PlayingAgainstType:
** As the leader of a group of aliens heading to Earth in "Earthbound", Creator/ChristopherLee is cast, for once, in a sympathetic role.
** "Death's Other Dominion" has Creator/BrianBlessed playing the straight man to John Shrapnel's hammy ravings. You read that right, Creator/BrianBlessed GIVES THE MORE RESTRAINED PERFORMANCE.
* HeyItsThatGuy:
** Christopher Lee, as mentioned above.
** Also guest appearances by [[Series/ToTheManorBorn Peter Bowles]], Ian [=McShane=], [[Series/{{Dynasty}} Joan Collins]], Creator/BrianBlessed (twice) and Julian Glover, amongst others.
** The main villain of the last episode was Creator/PatrickTroughton (best known from ''Series/DoctorWho'').
** Bergman was played by [[Series/TheFugitive the original Lt. Philip Gerard!]].
* TechnologyMarchesOn: The Alphans' Commlocks: a combination of portable computer, communicator, TrackingDevice, identification item and security key are essentially a somewhat bulkier version of today's smartphones with that consumer item taking on nearly all those functions and more.
* TroubledProduction: Suffice to say, it had its moments.
** As an example, the story goes that the model that portrayed the titular "Infernal Machine" was so literally infernal to manipulate, that the special effects artist ''[[TrashTheSet tossed it across the room]]'' when the final take with it was done.
* TypeCasting: The one villain who was undoubtedly played for laughs was cast and voiced by Bernard Cribbins ("Brian the Brain").

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