As far as I know, there are 5 other Firefly references in-game.
-Mudder's Milk
-Saffron Reynolds...the poison vendor (can't tell you how much I laughed at that when I first saw it in Wrath beta). There is also a "Yolanda" across the way from her.
-K. Lee SmallFry, an engineering trainer.
-Capison 38 engine quest
-Flavor text on the Captured Firely used to read "Still Flying"

Let me know if I missed one

Don't forget the "An Antique Gun" with the flavor text "The name 'Lasitor' is etched into the barrel"

My fail for not being able to link items.

Now where's a "Big Damn Heroes" quest? Hmm, or maybe "I Aim To Misbehave".

Dammit, now gotta go watch the show again. Back in 13 hours.

Ohhh...I just remembered there are also Ogres named Fanty and Mingo

http://www.wowhead.com/quest=25535 is also a quote from the Firefly movie Serenity. I got all giddy myself when I realized that.

What Doctor Horrible references are there?

@Keegan

Isn't there a doctor terrible in icecrown?

So there is! Surprised I never found him. Pity he doesn't say any quotes from the show on aggro.

Still, any nod to Dr.Horrible makes me happy.

There's also a Dwarf in Wetlands who uses "gorram" a bit in her speech. ^_^

My guild's name on Vek'nilash is Big Damn Heroes. Love me some Firefly.