I was thinking recently about the combination of two very different SF universes: Whedon's Firefly / Serenity and Karl Schroeder's Virga series. No, I am not completely insane. If you are familiar with both, please let me explain...
The Firefly 'verse is (as explained in the movie) a single star system with dozens of habitable planets and hundreds of habitable moons. If you have taken a basic astronomy course, then you know how it is likely that there is only one planet (at best) in the "green zone". That is where water is liquid, so the planet is not too hot like Venus, nor too cold like Mars. You can't pack a bunch of planets into the green zone because they would perturb each other's orbits, at best flinging themselves out of the green zone, at worst into the sun or on collision course with something else. This all would occur shortly after the solar system itself formed, so you'd never see dozens of fully formed planets in the green zone in a mature star system.
Even though I really enjoyed the series and the movie, Whedon's attention to scientific realism is almost non-existent. I realize that Whedon's goal is not plausibility, but to tell good / fun stories. But if a SF work is going to reach my highest regard, it has to take care of all the details I can think of.
Karl Schroeder's Virga is basically a giant ball filled with atmosphere. There's a large central sun called Candesce (which is artificial) and a bunch of smaller ones. This large space is populated by humans living in free-fall (no gravity).
Virga is apparently constructed with advanced molecular nanotechnology, which implies superhuman intelligences. These entities decided to make a zoo / game preserve and populate it with regular pre-singularity humans. Perhaps to see what kind of societies would form when living in a free-fall environment. And by interfering with the operation of electronics (a strong EMI field pervades Virga), their tech level is limited it about 1940's level, but without much electronics.
At any rate, the Virga setting provides the environment and scale that is really needed for the Firefly 'verse. The towns and cities are days and sometimes weeks of travel between each other. The Firefly central planets have a mid-21st century tech level (at least in terms of computers and medicine) and the border moons have mostly 19th century tech, so the overall tech level is about right.
Actually, with Virga you don't need the massive energy requirements for interplanetary travel (or more realistically Star Trek style interstellar travel). Jet powered vehicles of all sizes are used in Virga now.
The Firefly computers and Internet (called the Cortex) are not really a problem, most of the shows don't revolve around that. With regards to electronics in general, we might decide to modify Virga's EMI field a bit. Maybe open up the lower frequency bands to allow at least AM radio and other primitive electronics to work. You definitely don't need to allow for high speed electronics. So no video calls, which would impact some scenes a little bit, but I don't think the overall story or pacing would be affected.
You'd still have the Alliance and the core worlds (now just cities). The Alliance vs. the Browncoats is actually quite similar to the struggles of the large and small nations described in the Virga novels.
What got me thinking about this combo of SF universes was really the Reavers. The idea that these ultra-savages still have enough discipline to run spaceships is absurd. If our own space exploration is a guide, then even with very highly trained and non-batshit-crazy personnel, there are plenty of opportunities for fatal accidents. In a more "realistic" SF universe, the Reavers would have killed off themselves immediately.
However, in Virga, it works. The Reavers don't need to worry about atmospheric containment, complex navigation, really high energy systems (like nuclear fission / fusion reactors) and all that stuff. They could plausibly maintain (at least for a short while) 19th century level tech. Or heck, have them ride flying dragons or something.
So if we wanted to re-do the episodes, we'd need to re-do a lot of the visuals, mostly the exterior shots and anything that takes place apparently on the surface of a planet. Instead of landing on planets you'd be docking in towns and such. For the outdoor scenes we need to invent some new kinds of wilderness that don't exist in Virga now. And I think we'd need flying zero-gee horses or something. The ships wouldn't have interior gravity, unless we spin them or something. Perhaps it would be better to re-shoot everything, or else make CG models of all the actors and do the whole thing that way.
Episode-by-episode revision notes:
Serenity (series pilot): Instead of cryo-sleep, maybe just have River in a drug-induced coma.
The Train Job: Have it be a convoy instead. Paradiso could be a mining town next to a floating asteroid. They're not terraforming planets in general, but making new towns and "settling" chunks of matter (dirt, water, forests, etc.) floating about.
Bushwhacked: Might still need "space suits" for warmth, the outer reaches of Virga get cold too.
Shindig: Mostly the action takes place in town, so no major changes. Zero-gee cows or spin Serenity for artificial gravity?
Safe: Just need to figure out what the village in the hills would be exactly... a small town wheel, or maybe the people are living out in the wilds.
Our Mrs. Reynolds: Wagon pulled by horses may become a small ship pulled by flying animals. Have to change some details about the capture field, but that's not a big problem. Might need Serenity stuck in a jet-stream like current which keeps in on course with the capture field.
Jaynestown: Giant clay asteroid next to the mining town.
Out of Gas: Takes place in the cold outer area of Virga. Need to modify references to running out of air to be something else. Maybe just make it about not being able to go and hypothermia.
Ariel: No advanced computer tech, so no fancy MRI w/ 3-D virtual interface. Have Simon find records of the mind-altering drugs and other procedures performed on River. Scale back the medical tech a bit in general.
War Stories: Wilderness will need to be revised as usual. Wash flies Serenity to dock with Niska's town wheel at night, without the use of the jet engines... noise would alert the guards.
Trash: The floating villas now don't need anti-gravity to float above a Virga-style ocean.
The Message: This one is a problem, organ transplant and genetic engineering implies a higher level of tech than the proposed universe can allow. Need to have Tracy smuggle something else.
Heart of Gold: The bordello is a small town wheel itself. Flying horses again.
Objects in Space: Vacuum not a danger of course, though getting shoved off into open air without transport could easily be fatal. Though it worked out for Venera Fanning.
Serenity (movie): Much more use of video that would need to be fixed. How to re-do the opening sequence? How does Mr. Universe figure out what triggered River? River managed to find a scrap from an old map that mentions Miranda. The crew try to look up Miranda in the latest set of paper encyclopedias. Mr. Universe may just have a big AM transmitter, though are people going to be convinced by an audio broadcast the way they might be for a video broadcast? Maybe have Serenity bring back more hard evidence from Miranda.
So yeah, you'd have to re-shoot the whole thing, but the stories and characters would mostly be unchanged in the new setting. And make a whole lot more sense to boot.