They couldn't fly on their own, because they were all out of ki from doing to Super Saiyan God ritual. After their battle, Beerus falls asleep in attempt to destroy Earth so Whis takes him home. Goten is curious on how being a god felt for Goku while he was having his big feast. ...
Bills, the God of Destruction, hearing that a Saiyan has defeated Freeza, awakens from a long slumber. Bills tracks down Son Goku and challenges him to a fight… I read Dragonball Z as a manga. I didn’t watch the series as an anime nor does the anime bring any justice to the story...