Just a quick one: io9 have an interesting little article here where a few scientists talk about which science fiction depicts their field most accurately.
And what’s not so accurate:
“Whedon et al. also seem not to realize how big space is, even within our solar system. You can’t make a blockade in space. To give you an idea, the “asteroid belt” in our own solar system is supposed to be this incredibly dangerous region with rocks everywhere. In reality, the distance between big asteroids is more like a million miles.”