To the best of my knowledge, there is no way to gracefully exit the game without a mouse, so I had to hit the reset button.

Well, if you're in-game you can goto the console (~) and enter "quit" and that will exit the game (just like every other FPS engine past Quake). Thing is, it doesn't work if you're in any kind of menu. Then, of course, you could just give it the three-fingered-salute and kill the process.