I'm in the process of hooking my best friend on Firefly, and upon the scene in which they run away from the Reavers at the end of 'Serenity,' she squealed and declared, 'I know what a Crazy Ivan is!'
Apparently it's a submarine term, used during the cold war by the Russians, which means to do just what Serenity did - to turn around to see if someone was behind you, and generally they shoot right past you and you can run the other way.
This bit of completely useless but faintly interesting trivia brought to you by the letters N and G.
Well. /I/ thought it was interesting, anyway. ;)