Bad Sci-fi physics.

I once read a Simpsons comic where the geeks that Homer helped at university got money to make a sci-fi movie and they did so according to proper physics. Of course everyone was disappointed when there was no sound in space, no fire in the explosions and the journey to nearby stars took several years. In the end only the geeks and The Comic Book Guy are left in the theatre as everyone has walked out.

You have to have some fantastical elements to make it interesting but not always. Serenity did very well with having no sound.

Anyway over here they decided to write a report card on a few items of physics. They looked at the following...

• There's no sound in space
• Not all planets have Earth gravity
• Planets should have diverse climates, instead of one unified climate across a "desert planet" or "forest planet."
• It shouldn't be too easy to communicate with alien creatures, without some kind of high-technology "translator" explanation.
• And it definitely shouldn't be too easy for humans to interbreed with aliens.
• Humans exposed to vacuum without a spacesuit shouldn't explode or shatter. And a "hull breach" where the ship's crew is exposed to vacuum should kill everyone instantly.
• You can't have fires in space, unless there's oxygen leaking out somehow.
• Asteroids or other objects shouldn't be able to float close together without falling into each other's gravity
• People shouldn't be able to dodge lasers and other speed-of-light weapons
• And there's no reason why someone would move in slow-motion in zero gravity.
• Faster-than-light travel is probably not ever going to be possible.

Follow the link and see how they rated 18 big name movies.