Look, since they usually involve smartass aliens, robots and magic powers, space battles have never been expected to the bastions of scientific accuracy. Still, it's interesting seeing just how much is wrong with the epic showdowns in stuff like Star Wars.
This clip, while based on a pinch of conjecture, uses science to break down some common mistakes and misconceptions when it comes to killing things with spaceships, then show us a few simple alternatives/possibilities for getting it right. There are obvious things, like the fact there isn't any sound or oxygen, but also interesting touches you may not have considered, like the fact lasers lose focus the further they travel.
The concept of starships becoming "hot pockets" is both delicious and terrifying at the same time.
The Physics of Space Battles [YouTube, via Laughing Squid]