Do I need to do anything to protect my pool during a rare freeze?
I honestly doubt that it will freeze over in that time, as the water will take some time to get anywhere near freezing temps.

If you are worried anyway, a good idea is to leave the filter pump running. Water that is still will more easily freeze over.

Of course, if you were truly worried, you could make it into a salt water pool, dropping the freezing temperature by a few degrees more.