Some examples of "bad science" that's obvious even to a non-science person, and thus distracting:
- A human exposed to the vacuumed of space only freezes and/or suffocates, without body horror.
Except most of the "body horror" you see in such scenes in fiction is exaggerated, to a ridiculous degree in something like
Total Recall or
Outland. There'd be some swelling, rapid desiccation of exposed tissues, maybe a little bleeding from the eyes, but it would probably be subtler than what something like
Event Horizon showed (though that handled it better than a lot of other things).
Also, showing a person quick-freezing on exposure to vacuum is getting it backwards. Vacuum is an
insulator! With no material to conduct or convect heat away, the only mechanism for heat loss is radiation, the least efficient one. Just as you lose heat more quickly in water than in air, because it's a denser medium, it should be obvious that you'd lose heat more
slowly in vacuum, but for some reason, nobody thinks this through. In reality, spacesuits need cooling systems to keep astronauts from overheating. (Also, surface moisture would boil away as vapor due to the pressure loss before it could freeze into ice.)
- Aliens resembling humans to excessive degrees, physically and/or culturally
Necessary poetic license if you want to tell stories about aliens using human actors. There's a difference between getting something wrong out of ignorance and making a deliberate break from reality for the sake of the story.
There was a vogue for a while to set TV shows in humans-only universes or nearly so, e.g.
Firefly, the
Galactica reboot,
Killjoys, and
Dark Matter, but that can be limiting.
- Living humans can be frozen and thawed, just like chicken drumsticks. Thing about the chicken drumsticks is, they're dead. And humans die when frozen. It's called hypothermia.
Unless you're talking about stories where it happens accidentally (e.g. Captain America), the assumption is that future medical science has found ways to keep people alive in cryogenic suspension. There has been active research in the field for decades, and there has been some progress made -- for instance, I've read recently about promising research into animal torpor/hibernation and the possibility that it might point to ways that induced hypothermic torpor could be used to keep severely injured or ill patients alive long enough to be treated, or allow astronauts to hibernate long enough to reach Mars.
In my
Arachne trilogy, the crew of the title ship is kept in hibernation during an interstellar journey, but they're not completely frozen. From what I've read, the best medical science is likely to be capable of is to slow life processes by a factor of 10-12, so that a hibernating person might age roughly a month per year. The hibernation system in the trilogy also keeps the subjects' brains stimulated so that they experience an ongoing dream state, since I'm skeptical that you could shut a brain down completely for a long time and then start it up again.
On the other hand, I like faster-than-light travel, and don't like eggheads telling me it's impossible just because our current limited knowledge of the universe says so.
The current "egghead" consensus is that it's theoretically possible but likely to be prohibitively impractical due to the enormous energies involved, and might be restricted in certain ways in order to preserve causality. But theoretical advances over the past few decades have made it marginally less prohibitive, so there's always the chance that there could be more breakthroughs in the future.
Same goes for thinking all life must be Earth-like. IMHO these aren't common-sense issues like the cryo-freezing or the exposed-to-the-vacuum-of-space thing. These are just a lack of imagination.
Which is easier to avoid in prose, or maybe animation if the designers are creative enough, than it is in film or TV. The conceit in the original
Star Trek was that there were plenty of non-Earthlike worlds in the galaxy, but the ship's mission parameters would lead it to travel mainly to the more Earthlike ones that could be depicted on a 1960s TV budget.