Well, the mysterious lack of Asians in a world run by the Anglo-Sino Alliance, and possibly the gender roles in some places, but that's going to the side today because it's messy and I want to talk about something else.
Namely, the science. It occurred to me a few days ago that there isn't really a lot of hard science in the show, and what sci-fi elements there are, are mostly in the background and never explained. (This isn't a criticism. As I kind of indicated above, I'm not big on technobabble unless it's by a mad scientist.) However, because I weirdly like ascribing science to fiction and because I'm curious just how much "science" there is in the show, I'm going to make an annotated list. (I'm not including Serenity, the movie, though. I'm pretty sure I'd miss something if I included that.)
If you haven't seen Firefly, be aware that there will be spoilers in this list. Actually, what am I saying? If you haven't seen Firefly, close this window and do so right now. Then come back and join the discussion.
- Serenity, the spaceship - We never learn what kind of propulsion system it uses, and what we see of the engine is basically a bunch of moving parts that look cool. However, the exterior shots of the ship look like it's got some sort of ion drive. The "wing" engines on each side of the ship seem to be jet engines, used when in an atmosphere. They pivot, so the ship can fly in any direction. Serenity also has a life support system and artificial gravity.
- canned protein - A dietary staple on board. It makes sense, since you can't keep fresh food fresh for the length of time it takes to travel between planets.
- the Cortex - a.k.a. the Internet, except shinier and with better graphic design. Communication comes through in "waves", which, if memory serves, get bounced from place to place until they catch up with the receipient.
- the Alliance ships - Actually, I'm not sure if they're ships or space stations built in the middle of nowhere. They're certainly big and fairly city-shaped and imposing. Designed to house and train attack forces and wage wars, I'd imagine.
- the Alliance's Sonic Rifles - What it sounds like; capable of throwing a man for yards. I'd imagine we're talking very low-frequency pulse, with high power and narrow scope. We're already using sound as a weapon, though we haven't scaled the system down to a mobile size.
- laser guns - Also what it sounds like. I think we only ever see on, an obsolete model, and it's been a while for that, but I've had reason to research laser weaponry and that gun? Has to have a new kind of battery. Lasers require an incredible amount of power, and not one that's likely to be portable.*
- automated garbage pick-up - Again, what it sounds like: flying robotic drones that grab garbage containers and fly them to a dump.
- floating estates - Once you've mastered artificial gravity, antigravity, which appears to be what holds up the estates in "Trash", can only be a step behind (or was it first?).
- terraforming - We're told that a number of planets are still undergoing terraforming efforts, but we never see anyone terraforming anything. We do see the efforts in progress though, in the visuals of California scrub on the more "rural" planets.
- HOB rods - Thin rods that emit ultrasonics that cause internal cranial hemorrhaging, followed by death.
- the experiments done on River - River's amygdala, we're told, has been stripped of myelin. That would have to be massively invasive, very precise surgery, since myelin coats neurons, and the amygdala isn't the most accessible part of the brain.
- the brain scan - In "Ariel", Simon takes River to a hospital for tests. The imaging system is an interactive hologram. If this is anything like today's technology, there would be a host of cameras and sensors trained on the hologram area to detect movement. I'm not sure how the hologram's made visible—there's obviously no mist or glass to make the light appear as strong as it does.
- the 'suspended animation serum' - An ex-comrade of Mal's reappears in a corpse-like state so realistic that Simon starts performing an autopsy. He'd been in that state for several weeks, and (again, if I remember correctly), there was an injection involved. So far, the only suspended animation we've achieved has been with a) cold or b) gas, so the injection's something new. It would work on the same principles of slowing vital signs and lowering body temperature, though.
- Niska's space station - Self-explanatory.
- Reavers - Humans who've gone mad from a space-induced cabin fever (according to the TV show) or a drug that's supposed to make everyone happy and complacent, and which backfired in a small but significant number of cases (according to the movie).**
That's more science than I initially thought, but as I said, it's all backgrounded, glossed over, never explained. Very good world-building, though, in that watchers are led to take it all for granted from the start, and a fair bit of the science interconnects (like the gravity manipulation stuff, and the sonic weapons).
There's a lot of fine background details in Firefly actually, all of which betray an extensive world-building session (or ten), and not a huge amount of exposition on top of it. That's how world-building should be, in my opinion. It's certainly how I try to go about it.
*not that that's stopped me
**It's highly likely that I've missed something. Let me know, if I have, and I'll add it. (Working from memory here.)