Quote Originally Posted by Siegfried View Post
Mog never flies during any part of the game.
He flies on the airships

To be serious though, I just saw it as being one of the more cartoon-y aspects of the game that FF games just have every now and again. After all, it's not terribly realistic that with just a helmet the party could travel along the Serpents Trench, it's just slight bends in the laws of life to make a plot move along.