I've noticed that Duke has a dry patch on his ear. It's rough and kind of leathery with no hair in the area. I don't know what this could be. I saw a post where someones bunny had bumps on his ear which turned out to be ear mites, but Duke doesn't have anything in the inside of his ear that I can see, just the back of it. My other bunny Beau had earmites when we got him and he had full blown cankers and he never had bumps on the outside of his ears. I tried to call the vet but they were closed for a holiday. Anyone have any experience with anything like this?

It is too difficult to really get a possible idea of what might be going on by looking at a picture.  But sometimes ear flap skin conditions can be caused by inner ear problems- such as mites, infection, swelling, etc.  Can you see anything by tring to look at the ear itself- in the ear?  Does the ear smell (infections can smell)?  Unfortunately with cats, dogs and bunnies- in order to see deep in the ear canal- where most problems start you need an otoscope and someone experienced to check the ear- to know what they are looking for and to not rupture the ear drum by poking into the ear too far.  The ear canal extends beyong what you can see by looking into the ear.