Well, he takes some liberties. For one thing, it's obviously impossible for one guy and his sons to build an ark that big, so in this version they are assisted by giants. Which, interestingly, were mentioned earlier in Genesis (but not in relations to the flood story). There is also a stow-away. There are also giant six-armed angels. And the problem of animals eating and defecating on the boat is solved by having all the animals immediately go to sleep upon settling down in the ark (which is a pretty good solution if you can figure out how to do that).
With the Christian God being able to make things ex-nihilo, you would think a more elegant solutions to God's dilemma would be to simply 'poof' every thing out of existence and start over with new 'Adam and Eve' and a command built in not to 'sin'
Humans don't seem to be able to follow the God/Christian rules....also you would think a creative God would know this and fix it or make allowances. Stupid stories and religion.