Dean is pretty sure Dan can see right through him, but he doesn't really care aas long as he doesn't get called out on it.

"Yeah, he'll be fine. He's probably gone back into town to call search & rescue, or something. Maybe they'll eve bring in a helicopter."

He doesn't comment on the voices thing, but he certainly notes it. He's pretty sure he heard voices saying similar things when he woke up, too. Maybe it's a Battle Royale situation and they've been dropped in the middle of nowhere to duke it out with those monsters.