Actor Allusion: Back to Earth does it. The crew meet Craig Charles, who plays Lister, and Rimmer asks for his own sitcom (Chris Barrie starred in The Brittas Empire, which alluded to Brittas having a similar event occur in his past to Rimmer).
Cat's 'Do I dance?' from "Parallel Universe" might be an example. A more prominent example is the Blue Midget dance from "Back in the Red".
The movie is infamous for being stuck here. Originally planned to go into production after Series VII, it got as far as having a script reading by the cast, filming dates announced and a prosthetic test for Robert Llewellyn. Unfortunately, thanks to continuing issues with funding, it never got any further than that. All that remains of the project is a test model shot using the Remastered ship, included on the Bodysnatcher Collection DVD set, and about 35 script drafts, with some of the ideas from the drafts reused as the series X episode, "The Beginning".
The series itself was originally supposed to be filmed and aired in 1987, but was delayed by an electricians' strike.
Doing It for the Art: Back To Earth, despite its small budget, looks quite impressive for a TV production. This is because several members of the production team actually worked for free; the CG Skutter seen in part 1 was done entirely by one person for no pay, simply because he loved the show so much.
As Danny John-Jules loves to complain on DVD commentaries, there are many examples. Don't get him started on how everybody else's career took off except the main cast!
Cassandra, from the episode of the same name, is played by Geraldine McEwan (of Henry V and Robin Hood: Prince of Thieves fame).
Craig Charles lampshaded this when they were filming the reunion scene with Selby and Chen. He replied to Kryten's question, 'You know these people, sir?', exclaiming, 'Of course I do - they're in EastEnders!'
As is Kill Crazy, incidentally.
And now, so is Baxter.
The US pilots had a ton of these — Tom from Scary Movie 4 played Lister, Daphne Moon popped up as Holly, Jadzia Dax appeared as the second cat (the first was played by Hinton Battle, who isn't a particularly well-known actor but is pretty legendary in the world of dancing), and Kryten was played by... er, Robert Llewelyn, who was Kryten in the BBC series Red Dwarf.
Apparently, Hinton Battle is a hero of Danny John-Jules. Battle apparently put a lot of work into his version of The Cat, making John-Jules something of an Ascended Fanboy.
Holly, the ship's computer and most notable example, was played by Norman Lovett for Series I-II and was replaced by Hattie Hayridge for Series III-V before being Put on a Bus in Series VI. When the character returned for Series VIII (and the Series VII finale), Holly was once again played by Norman Lovett.
Kryten, the mechanoid, was a one-off character in Series II played by David Ross. When he became a regular in Series III, Ross was unavailable and Robert Llewellyn replaced him for the rest of the show's run.
Talkie Toaster (Exactly What It Says on the Tin) was voiced by John Lenahan in Series I and II (although his scenes were cut for the latter.) When the character resurfaced briefly in a Series IV episode ("White Hole"), not only was he voiced by David Ross (the original Kryten) but the original prop had been replaced as well.
Kristine Kochanski was a guest character in Series I, II and VI, and played by Clare Grogan. When the character became a main character in Series VII, Grogan was unavailable and ChloŽ Annett replaced her.
Rimmer's father was played by John Abineri in series II. After Abineri's death, in series X, he was played by Simon Treves.
Name's the Same: "Lemons" has the Dwarfers travel to the past and end up meeting a traveller named Jesus during the years little was chronicled about him...but then it turns out Jesus was a common name back then...
No Budget: Dwarf is no stranger to this, but the most significant example is Back to Earth. The concept grew from short clips celebrating the show's 20th anniversary, to a full-fledged three-part production filmed in HD; unfortunately, the budget did not. The ill-fated movie also went through several rewrites based on wildly fluctuating budgets.
Paying Their Dues: Of the four original main characters, only one was played by an experienced actor. Craig Charles (Lister) was a poet, Danny John-Jules (The Cat) was a dancer, and Norman Lovett (Holly) was a stand-up comic.
The Pete Best: Kryten first appeared in a one-off appearance in Season 2 where he was played by David Ross. The character proved popular and opened up more storytelling possibilities, so Grant and Naylor decided to bring him back as a regular — Ross was unable to take the role due to scheduling commitments, however, so he was replaced by Robert Llewellyn (with a Hand Wave about how his appearance and personality was now different). Llewellyn proceeded to make the part his own, and even write some episodes.
Derailed by large hiatus at peak of UK popularity.
Also completely changed the course of Series VIII. Originally, it was going to end with a two-parter, culminating in the crew finally returning to Earth but obliterating civilisation as they arrive. However, circumstances meant the hour-long series opener had to become a three-parter, another episode had to become a two-parter and the series had to finish on a cliffhanger.
"Meltdown" was intended to be the opening episode of Series IV. However it was moved to the sixth and last episode because of concerns that viewers would consider it insensitive due to the Gulf War. If hostilities had continued, it might not have been shown at all.
Too Soon: The running order of Series IV was changed because of the Gulf War.
Troubled Production: The making-of documentary for Series X makes the entire production process sound like an absolute nightmare for Doug Naylor. The fact that four episodes were shot whilst the remaining two were still being written thanks to significant production cock-ups on behalf of the producer is just the tip of the iceberg.
A deleted scene from Series II has the Cat and the Toaster singing a duet. Sadly, the Toaster's lines were never recorded.
The first series would have ended with the episode "Confidence and Paranoia", and would've had a cliffhanger ending with Kochanski being resurrected as a second hologram. But as the planned second episode "Bodysnatcher" just wasn't working, they scrapped it, rewrote the ending for "Confidence and Paranoia" to have a duplicate of Rimmer activated instead, and wrote the episode "Me^2" as a new series finale.
Similarly, the planned opener for the third series would've been an episode titled "Dad", which would've resolved the cliffhanger of Lister's pregnancy and re-introduced Kryten on-screen, as well as having Lister give birth to a single baby boy. Again, the episode wasn't working so it was scrapped and replaced by a comically-rapidOpening Scroll (which also resolved the "Where do the twins come from?" dangling plot thread for good measure).
A third Red Dwarf novel co-written by Grant and Naylor, titled The Last Human, was being planned before their writing partnership split. (Naylor later re-used the title for his own novel, even though the stories were different.)
The eighth series finale "Only the Good..." had four different endings altogether. The original ending (which was filmed but not used) was a happy ending where they saved the ship and took it back for themselves. The second ending (written, but not filmed) was a Downer Ending with Rimmer trapped aboard the disintegrating ship. The third ending involved Ace Rimmer coming to the rescue at the last minute — this was ready to be filmed, to the extent that Chris Barrie was in his Ace costume, before the broadcast ending was thought up and hastily thrown together.
And before that the final episode was to be entitled "Earth" and have a Bittersweet Ending where they returned to the homeworld, accidentally destroyed all our epic monuments trying to land, and finally Lister swaps insurance details with the survivors. They really couldn't afford it.
There was originally supposed to be more flashbacks in the style of Lister's one from "Balance of Power" to highlight Lister's loneliness.
In the commentary for the second episode, Chris Barrie mentions that he originally auditioned for both Rimmer and Lister, and *preferred* Lister. Imagine that for a moment. "Bodyswap", in fact, gives us a taste of how he would have played it.
Similarly, Norman Lovett originally auditioned for Rimmer. Craig Charles got on board because Grant Naylor asked him if he thought the Cat was a potentially racist character, and Charles liked the character of Lister enough to audition.
Series X was initially intended to have 2 weeks worth of on-location shooting, 13 days of which had to be sacrificed in order to allow for the inclusion of a live studio audience for each episode. This also resulted in the cutting of two episodes that were going to use on-location footage heavily and feature a returning Kochanski as a prominent character.
There was, at one point, a Christmas Special in development, which never made it off the ground. Bill Pearson built a single model for it, which was recycled as the Simulant Death Ship in "The Beginning".
Mugs Murphy, the cartoon gorilla who appeared briefly in 'Confidence and Paranoia,' was originally going to be much more prominent, and Grant Naylor even considered an episode in which he would be brought to life.
Had the special effects budget allowed it, Rimmer would have been monochrome, as he appears in the Smegazine comic strips.
Word of God: In a weekly podcast for the TV channel Dave, Doug Naylor explains that Rimmer was brought back as a hologram to keep Lister sane, and as a result his holo-computer makes it so he ages at the same rate as Lister. This neatly paves over the issue of how Rimmer both doesn't age a day during his six hundred years on Rimmerworld but still ages at the same rate as Chris Barrie.