This was one of the first things that made me realize the Bible was just a collection of stories. Archaeologists keep coming up with more finds of early human inhabitation all over the world that predate the dating of the flood story.
I've asked JWs on occasion if Noah was able to travel to Eqypt and Africa, for instance, to preach to all those people before the flood.
You just get a blank stare, or they try to say that the dating of these civilizations is inaccurate (this is what the society has said, therefore it must be true).
Mostly, though, I have gotten no response. You can lead a horse to water....