When Ferdinand asks the hedgehogs what happened to Tres? The hedgehogs make the sign of the cross but Una the female hedgehog does it with her left hand. In the Catholic religion the sign of the cross is always done with the right hand.
Ferdinand is named Ferdinand from birth, when he is being raised at the bull camp. He then runs away and is adopted by a new family, but how does this new family know that is name is Ferdinand? He was not wearing any identification tags, and he clearly couldn't speak to the humans to tell them this.