Being a part of the equine community, my favorite is when people go on a trail ride once or twice and consider themselves expert horse people. Hello?! You were riding in shorts and tennis shoes on a horse that knows nothing but "follow the leader." When your shoe gets caught in the stirrup and you get dragged, don't go complaining about how it was the horse's fault.
People in the horse community use the terms foal, filly, colt, gelding, stallion, mare and pony in the correct context and are also aware that ponies and miniature horses are not the same thing.