I've never seen one accidentally left on, but I'm sure it's happened.

The "danger" zone of the radar is only 2-3 feet in front of the aircraft as modern radars are only about 25 watts. Also, when we're dow low (approach/departure) or on the ground it's tilted several degrees up to get a better look at the weather.

I.E., your flashlight and batteries are perfectly safe, if you know what I mean.