- Approval of God: When author Robert Graves came to see the filming, he loved it so much, he refused to leave. His only comment on the acting was that George Baker was just the right height to play Tiberius.
- Cast the Runner-Up: BRIAN BLESSED originally auditioned for the role of Tiberius, but was eventually persuaded to play Augustus instead. He recounted Herbert Wise's saying "be as you are, full of flannel", and that he should always play Augustus as an ordinary person, because the reactions of those around him would make him the Emperor.
- Dawson Casting: Because the series takes place over nearly eighty years, this is both played straight and later inverted with many of the same characters. Just to name a few major examples:
- Derek Jacobi, aged 38, played Claudius from the age of 19 to his death at 63.
- Siân Phillips, aged 43, played Livia from the age of 34 to her death at 86.
- George Baker, aged 45, played Tiberius from the age of 18 to his death at 77.
- Margaret Tyzack, also aged 45, played Antonia from the age of 27 to her death at 73.
- Some examples where this is purely played straight include John Hurt (aged 36) as Caligula from the age of 17 to his death at 28, Christopher Biggins (aged 28) as 17-year-old Nero, and Graham Seed (aged 26) as 13-year-old Britannicus.
- Dyeing for Your Art: George Baker, who was in his early forties, went on a regime of diet and exercise so he could realistically play a young Tiberius. He managed to equal the weight he used to have when he was twenty-four. It sort of doubles as accidental Enforced Method Acting (does that even exist?) as his tiredness and exhaustion from working out so much and eating so little actually made it easier for him to play an often frustrated and bitter character prone to mood swings.
- Enforced Method Acting:
- On early episodes, Derek Jacobi put a stone in his shoe so he would limp realistically. Once he got used to it, he didn't need the stone any more.
- George Baker lost a lot of weight to play Tiberius, which also made it easier for him to realistically play the mood swings, as the amount of diet and exercise provoked a lot of that for him in Real Life.
- Because of the alleged curse that'd already claimed some lives, BRIAN BLESSED was a bit anxious. While they were shooting Augustus' dying scene, there was a blackout. By the time they did the take, he was terrified he would actually die on set, so the terror in his eyes is authentic.
- Fan Nickname: I, Clavdivs (achieved by pronouncing the Roman U's as V's; later home-video reissues do away with the Roman styling).
- Missing Episode: The scene in episode 8, "Zeus, by Jove!" where Caligula cuts the fetus from Drusilla's womb was considered too shocking and was therefore re-edited several times, even on the day of its premiere by order of Bill Slater, then head of Serials Department. After initial broadcast and a rerun two days later, the shot of the fetus was removed so that the episode now ends with Claudius looking in shock and horror but without the audience seeing what he sees. The deleted shot was only shown twice in 1976 and is now lost since the BBC no longer has a copy of it.
- No Budget: The novel and its sequel, were big sprawling epics, with a few large battles, lots and lots of circuses and gladiatorial games, and the occasional riot. The TV adaptation manages to stage the whole thing without ever having a crowd larger than a meeting of the Roman Senate. (The battles all occur off-camera, with perhaps an aftermath scene in the general's tent; the gladiatorial games consist of a close-up camera on the Emperor's box.) Hey, The BBC ain't made of money.
- Retroactive Recognition: For fans of genre favorites and classic blockbuster films, along with Patrick Stewart and John Hurt, there is also John Rhys-Davies in the cast.
- Throw It In!: For Livia's dying scene, John Hurt suggested Caligula actually jumped in bed with her, as that would be more realistic for the character. They made the take, and he spontaneously kissed her full in the lips to emphasise the kind of degenerate person Caligula was (Livia was his great-grandmother).
- What Could Have Been:
And then, Laughton addresses the Senate... and soars. In one scene he becomes every belittled, misjudged man who ever stood up and said, this is not who I am. At last it is possible to understand why Laughton placed such significance on the interior. He was acting the other takes, and they were good; in this one, he is being, and it is art. — Self-Styled Siren, "Charles Laughton: Actor as Artist", Feb. 8, 2015.
- Charlton Heston and Ronnie Barker were considered for Claudius. Seriously.
- Helen Mirren turned down the role of Drusilla. Ironically, she would later star in Caligula, which funnily enough, also featured Siân Phillips' then-husband Peter O'Toole.
- The first attempt to do this for the big screen was Alexander Korda's production in 1937, with Josef von Sternberg directing. It had Merle Oberon as Messalina (more Dawson Casting), Emlyn Williams as Caligula, Flora Robson as Livia and Robert Newton as Cassius, and Charles Laughton as Claudius. It was to be a gigantic, lavish production filmed at Korda's Denham Studios, with sets designed by Korda's brother Vincent. The project was plagued with difficulties from the beginning, among them Merle Oberon sustaining injuries in a car crash and Laughton seemingly having great difficulty getting into the role. In the 1965 BBC documentary The Epic That Never Was, you get the history and background information, plus the outtakes of Laughton having to stop filming again and again. The project was finally abandoned as a train wreck. But Charles was not just being a drama queen. Trained as a stage actor, it always took him a while to kind of "find" the character and and speak and act just right. Skip to minute 55 to see how he finally did it.
Trivia / I, Claudius