Thanks! It's the butt that actually bugs me. It's a little too big. That leg is actually pretty close to the original image, but it might be that that image is just wonky. I didn't really check it against pony reality. It's just a vector that I found here on DA. I had a critic on Reddit tell me the same thing, but once he saw the image, he said the drawing was right on. It's kind of a strange position for a pony to be in so I'm not 100% whether the leg is good or bad.
Thanks for the comment, though. Since a couple of people have mentioned the leg, I'm sure it must look weird.