Originally, producer Derek Granger asked Anthony Andrews to play the role of Charles Ryder. Andrews, however, felt he was better suited for the part of Sebastian Flyte. Jeremy Irons, Granger's first choice for Sebastian, preferred to play Ryder, so the two actors swapped roles.
Castle Howard, which was used as the location for much of the series, was owned by George Howard - who at the time was the chairman of the BBC, a rival of the network airing the series. He nonetheless agreed not only to allow his castle to be used, but served as a technical advisor and supplied many of the props for the production, while also advising the filmmakers in ways to avoid incorrect portrayals of life in such an environment.
Production was delayed for several months by a strike of ITV technicians in 1979. When filming resumed, director Michael Lindsay-Hogg was no longer available because of commitments in America so he was replaced by Charles Sturridge for the scenes filmed in Oxford and many of the ones filmed at Castle Howard ("Brideshead").
During the enforced break in filming caused by the ITV technicians' strike in 1979, it was noticed by the cast and producer that an important scene (Julia in tears while sitting by the fountain at night) had not been included in the script. They decided that it should be put in. In fact, during filming, the cast and crew had only a vague idea how many episodes would result. The final script was apparently NOT written by 'John Mortimer'. Producer Derek Granger simply selected scenes and lines from the pages of the novel, though Mortimer still had to be credited for contractual reasons.
When filming the scenes during the storm on board the ocean liner, the small cabin sets were made to rock from side to side, but this could not be done for the much larger dining room set, so producer Derek Granger stood on a chair behind the camera and waved a stick from side to side to indicate to the cast which way to lurch and sway.
Laurence Olivier was offered his choice of roles in either Lord Marchmain or Edward Ryder (which ultimately went to John Gielgud). Olivier picked Lord Marchmain, but later regretted the choice as he realized that Edward Ryder was actually a much stronger role.
Sebastian's teddy bear, Aloysius, was based on a real one called Archie which belonged to John Betjeman, one of Evelyn Waugh's friends from his days at Oxford university.
In episode Brideshead Revisited: Sebastian Against the World, Lady Marchmain reads aloud the G K Chesterton "Father Brown" story "The Queer Feet" in which Father Brown says of a criminal "I caught him, with an unseen hook and an invisible line which is long enough to let him wander to the ends of the world, and still to bring him back with a twitch upon the thread". The episode titles (and the chapter titles of the book) "The Unseen Hook" and "A Twitch Upon a Thread" are a reference to this, as a metaphor for the way in which the characters are able to wander the world according to their free will until they are ready and receptive to God's grace, at which point He acts in their lives and brings about a conversion.
In 2007, the series was voted the 7th favorite series to air on PBS' "Masterpiece Theatre" in the US. Unfortunately, it had never aired there - it was shown as part of "Great Performances".