It was raining. I had my 3 pet wolves following me. I was riding my horse which was in full diamond armor, and I was fighting hostile mobs near my mine cart on rails. I just walked into the mine cart on my horse. my horse and I accidentally "mounted" the mine cart and were riding in it; I was on the horse and the horse was in the mine cart. The mine cart went off the rails and onto some dirt blocks with me and the horse in it. I tried to move, but my horse was crawling super slow and the mine cart was moving a just little. I got off the horse, and the horse was stuck in the mine cart. I could mount the horse, but I couldn't ride/move anywhere. When I tried to break the cart with my pick axe, it would only hurt the horse. I tried pushing the horse into 1 block deep water, but the glitch did not stop. I cannot get the horse out of the cart.