Actor Allusion: In a Comic Relief episode Uncle Albert mentions how nice it would be to walk through a door into the 1940s, which Rodney dismisses as stupid. Raquel then goes to bed and Del says "Goodnight Sweetheart.". Del then remarks that he is not a chief inspector.
This was also done the other way around—in Goodnight Sweetheart Gary (played by Nicholas Lyndhurst) is about to lean back and fall through an open bar door like Del Boy famously did, but notices in time and gives an Aside Glance wink to the audience—accompanied by uproarious laughter that must seem inexplicable and random to anyone unfamiliar with the Only Fools scene in question.
Due to music licensing laws, the BBC has replaced the original soundtrack on many episodes, and in some cases simply cut out scenes where the offending music is being played. John Sullivan's family were not happy with the results. The law on music licensing has since changed, meaning the original unedited episodes could now be released, but the BBC is yet to do this.
The same applies to the original version of "A Royal Flush," which is unavailable on any home video format (the VHS release had about a minute of footage removed, and the DVD release removed nearly ten minutes of footage and added a laugh track). However, the original cut still appears from time to time on UKTV Gold and other such channels, so it's not too hard to find decent quality versions of it.
In a straight version, several mini-episodes such as Christmas Trees, Licensed to Drill and the Comic Relief Special have never been released on VHS or DVDs.
Or what could have not been. Due to disappointing viewing figures for the first two series, the show was nearly cancelled altogether. However, the first and second series were repeated in a low key time slot in June 1983 and achieved respectable ratings, which convinced BBC producers to commission a third series. The show went from strength to strength thereafter.
Jim Broadbent was John Sullivan's original choice for the role of Del. While Broadbent turned down the role, he did later make three guest appearances in the show as DCI Roy Slater.
Enn Reitel, Robin Nedwell, and Billy Murray were also considered possible candidates for the role of Del, before it went to David Jason.
John Sullivan intended for Chas & Dave to sing the show's theme song due to the success from their "Rockney" style of music (a mixture of rock 'n roll and cockney). However, they were unavailable having just recorded their hit single "Ain't No Pleasing You", so Sullivan sang the song himself after being persuaded by Ray Butt to do so.
In 1986, David Jason told John Sullivan at a dinner that he wanted to leave the show and further his career elsewhere, so the fifth series finale "Who Wants to Be a Millionaire" was written as the final OFAH episode, and would have seen Del leaving England with his friend Jumbo Mills to run a car business in Australia. A spin-off entitled Hot-Rod was planned, which would've been all about Rodney running Trotters Independent Traders with Mickey Pearce. However, Jason changed his mind and decided to stay on, and Sullivan rewrote the ending to show Del rejecting Jumbo's offer.
Elizabeth Hurley auditioned for the role of Cassandra.
In the first chapter of the early 2000s Christmas trilogy, "If They Could See Us Now" (2001), The BBC wanted to get the rights from ITV to use the actual Who Wants to Be a Millionaire? gameshow with a special guest appearance from Chris Tarrant, but ITV refused because a plot point was that Del gave a correct answer and the quizmaster said it was wrong due to an error. They ended up with a blatant expy called Goldrush, hosted by Jonathan Ross.
Anthony Hopkins, a big Only Fools and Horses fan, was keen to appear in the series. John Sullivan even wrote the part of Danny Driscoll for him, but filming clashed with The Silence of the Lambs and he therefore had to pull out.
You Look Familiar: Jumbo Mills, Del's old friend and business partner, is played by Nick Stringer, who also appeared in the Series 1 episode "Go West Young Man" as an Australian to whom Del sells a car with faulty brakes.