Nerd polyfilla is what you do to make science fiction and fantasy make sense. It's imagining explanations to fill the plot holes left behind by bending of the laws of physics or plain clumsy writing. You can estimate the quality of SF through how much nerd polyfilla you need: some of it (Iain M Banks, China Miéville) needs hardly any. Others (bad episodes of Doctor Who and Star Trek) need quite a bit.

Star Wars needs enormous great skips-full of the stuff. It needed building merchant amounts even before the prequels.

Here's an absolute masterpiece of polyfilla — via BoingBoing, why R2D2 is, in fact, the secret leader of the Rebellion. Read, and wonder.