Can you tell whether a tooth is a baby tooth or permanent tooth, if you don't recall it falling out?

Yes. You can tell because baby teeth look different than adult teeth. They are usually smaller versions of the adult tooth. If you still are not sure, visit your dentist and he or she can tell by looking at it or taking an xray. There you can also find out what happened to the adult tooth.
I can. Usually baby teeth will get loose and there is a symmetry to both sides of the mouth of what's left. Look on the other side and see if you can tell. Otherwise , get a diagram of the baby and permanent teeth and see if you can tell. Last, but not least, see your child's dentist.