Scorpion,
If you can ask how we could know that the "original manuscripts" contain errors, then one equally well ask how we could know that they contained the story of the resurrection.
We have to deal with the Bible we have, not a hypothetical Bible in which one could imagine anything whatsoever could be written; to do the latter is to base one's faith on quicksand, an ever-changing foundation of speculation.
Now, as for your hoped-for further elaboration of my argument: I explained already why I must decline your invitation. It's not enough for you to declare without any argument of your own that you don't think my argument is inadequate and that you want to see more evidence; if such a debate weapon were allowed, any argument could be effortlessly defeated. If you want forum readers to take your objections seriously, you will have to put some effort into constructing a counter-argument that explains exactly why the mountain and tall-tree verses are insufficient to indicate that the Bible writers believed that the Earth was flat.
Joseph F. Alward
"Skeptical Views of Christianity and the Bible"
http://members.aol.com/jalw/joseph_alward.html