'Use' a condom machine in a bathroom, and get one of a surprisingly large number of condom jokes. "Before you attack her, wrap your whacker!"
Fire the nuke at something, and occasionally get one of a few random comments. "Just like Hiroshima / Nagasaki / Pearl Harbor!"
The portapotty company's logo is a sumo wrestler carrying one, with 'Porta-Pu: We Carry Your Load'.
Most of the vehicles are Titsubishis.
If there are two rabbits in an area, they will...do what rabbits are known for. And shortly thereafter, with a 'Pop!' there will be three rabbits. One area has a button you can repeatedly press to spawn rabbit after rabbit, who will all start this, and murder your framerate. One well-placed grenade fixes the problem, though.
Even better in the Redux rerelease on Steam where this now gets you an achievement.