 So when the youngest brother is struck with deer lungs, it expresses the notion that Red Horn is someone who will have lungs like a deer and therefore a fleetness of foot that will rival a cervid.Indeed, his victory in the foot race, the major event of this episode, is a mere confirmation of this achievement.So the name that is presented as a misnomer, turns out on an esoteric level to be an understated description for the spirit who travels as fast as an arrow.