I found it! In the cats bed!
Actually, it's a little bed I made out of two old towels and the heating pad. It's on my bed on the side I don't sleep on. They love it because it's warm.
The remote was inside the "envelope" of towels way over in the middle. There's no way it could have gotten in there, especially as buried as it was, without some help. Help from sneaky little kitties.