Most of the characters in F:NV pronounce Nevada the way that Clark County locals pronounce it.
I'm only so far so I hope that's true. That's the real issue for me. If the NCR troops are using the Spanish pronuncation that's fine: [censored] Californians are always mispronouncing our state's name.
For the rest of you wondering what this correct pronunciation is, it's using a hard a, like in "apple". The incorrect "tourist" way is using the long a, like in "avocado".