Inaccuracy of elevations over long distance

Hi, Can you please look at my last two maps?  They show a over 100' elevation change from beginning to end, and I know that this is inaccurate.  They were shot in Texas and it was nearly dead flat.  Can you please tell me if they can be reprocessed somehow, or what went wrong?  I am under a deadline on this one too, so anything you can do to help would be greatly appreciated.