When Johnny met the caretaker at the graveyard, he stitched up a long gash in his shoulder. Where'd the gash come from? You might think it was done by the guy who was messing with that fat girl, but doesn't Johnny's skin disappear when he turns into the Ghost Rider? How could a plain knife cut his skin if it was never there? The knife also melted, which proves that the fire spreads to the parts of his body that don't show.