It's obvious that, in Firefly, there are strong Chinese and American themes. But what other cultures have you observed?
There's obviously a fair amount of Arabic, "Inara" and "Nandi" being Arabic names and the guild appearing to be Arabic. I've also noticed a LOT of Russian influence. "Eto kuram na smekh" (River's codeword) is Russian, as is the surname "Tam" (which means "there"), and the names "Simon", "Zoe", and "Vera" are commonly used in Russia (though I'm not sure if they're actually Russian in origin [EDIT: I just looked them up, and they're not, but the point still stands, I think!]). Niska and his henchmen are obviously Russian.
There's also Badger with his British accent (not sure which part of Britain his accent's from, as I don't live there and don't know one regional accent from another), but we don't see many others like him.
What other cultures have you observed, and what thoughts do you have?
Edit: Okay, so "Tam" is supposed to be a Chinese surname. It is still a Russian word, though. :O