I'm surprised no one has mentioned the fact that Wash, in practically one of his very first lines (not counting the dinosaur dialogue), says "hold on travellers" as he darts the ship away from the baddies.
Actually I mentioned it in the other firefly thread yesterday.
http://www.travellerrpg.com/CotI/Discuss/showpost.php?p=337893&postcount=34
But well worth repeating. I don't think there can be any doubt that Firefly was heavily influenced by Traveller. I got a heavy Traveller vibe from the first TV commercial I saw for the show before it even aired.
I think some people don't get the same vibe as me is because they have a very specific, focused idea of what Traveller is and for the OTU setting is a big part for many not to mention no FTL communication, certain aliens, jump space, I could go on. Not saying that such a focused ideal is a bad thing, it is not. You like what you like. YMMV
R