I've previously discussed how science fiction often tends to botch up the whole science part with regards to terminology. There's a lot of things to know if you want to write good science fiction. Among other things, you should know what a galaxy is and you will need to be able to recognize the difference between a black hole and a wormhole. Trust me, you do not want to get those two very different things mixed up.
Still, there's a lot of things science fiction gets wrong and I think it's time to address some of these further facts. Let's begin with one of the most obvious problems, and that is the lack of microgravity. We've all seen so many films that feature this it would be far easier to list the films that actually do take the time to depict weightlessness. Unlike many errors, however, there actually is a practical reason for this particular one to be invoked. After all, science fiction movies are generally shot on Earth. It takes time and money to be able to produce convincing weightless effects. When you have a great director and a ginormous budget (as was the case for 2001: A Space Odyssey) you can produce some amazing effects, but otherwise the strings will be visible.
However, very rarely does this issue ever actually get addressed, and when it is, it's usually in little more than a character offhandedly mentioning "artificial gravity". No explanation is given for how this future technology is supposed to work. At present, there's really only two known ways artificial gravity could be generated, and neither one is usually shown to be at play. The first and less feasible option would be to have the ship moving at constant acceleration, which can temporarily create its own gravity (something like in the launch sequence from Conquest of Space). The second and far more plausible method would be to construct a centrifuge, like in 2001: A Space Odyssey.
Contrary to popular believe, there is in fact gravity in outer space. In fact, gravity is more or less the primary force that prevents all matter from being torn apart by the expansion of the universe itself. Ryan Stone was not so much floating as she was falling around the Earth's curvature. Gravity is also what keeps the moon in orbit around the Earth, the Earth in the orbit of the sun, and the sun in our galaxy. Putting it quite simply anything that contains matter exerts a gravitational force of some kind, the strength of which corresponds to the object's mass.
Now for an extremely frustrating one that very few movies ever seem to be able to get right. Space is a vacuum. We've all seen plenty of science fiction stories that involve great big space battles with lasers. Star Wars is especially guilty of this and it is really annoying. SOUND CANNOT TRAVEL THROUGH SPACE! There is no way that is possible. It's frustrating how few movies actually pay attention to this detail: Destination Moon, 2001: A Space Odyssey, and Gravity being among the few exceptions.
While we're on the subject of Star Wars, I think it's worth bringing up how asteroid fields actually work compared to what we see in the movies. In The Empire Strikes Back, Han Solo tries to evade a number of pursuing Imperial ships by flying into an asteroid belt, leading C-3PO to claim "the possibility of successfully navigating an asteroid field is approximately 3,720 to 1". Actually it's not. Real asteroid fields are ridiculously easy to navigate. Generally there is a huge distance between the asteroids, so the only way you could crash into one is if you are an idiot or if your intention was to crash into one.
So here are yet more scientific concepts that science fiction can't seem to get right. For a genre called science fiction there doesn't seem to be a whole lot of... you know... science. No where is that clearer than in science fiction films about outer space, where the most basic facts are tossed out the window. Why is it that there seems to only be three major films that actually show space as silent that are each released decades apart (Destination Moon, 2001: A Space Odyssey, and Gravity)?