Here we are again; if we decide to believe that God made all the animals come to Noah we assume one miracle, that a God did command all animals to move somewhere, than the actual trip can as easily be explained by another miracle. Maybe God made all animals able to walk on water, maybe God had them all teleported to Noah, maybe there wasn't any animals on the other continents before the flood etc. etc.
I fail to see how you can derive at anything from this kind of discussion, either you believe it is supernatural or you don't believe in it, sure it is annoying when christians try to prove the bible by science, the same science that they might dismiss on other occasions, but that how belief work; you pick what you like and go la-la-la when other things are brought up. It's like Randy Munchnik in Futurama who builds an ark when the polar ice caps melts filling it with same sex animals claiming: there are parts of the bible I like and parts I don't like.