I don’t think it would be possible for bonnet mushroom mycelium to grow beneath the skin and have the fruiting body break through the skin. The frog’s body doesn’t provide the right conditions for mycelium to grow. Imagine that in a human—it’s not possible. It is a very interesting mystery though. My bet is photoshop to gain notoriety.
Remember that every time man thinks he has all the knowledge on any subject, God throws him a Black Swan or a Duck-billed Platypus just to keep him guessing..............