When Shaggy finds the directions in the spell book, he reads "Middle north, the board with the knot". Later, when the gang are following the directions in the cabin, Velma reads "Follow the middle nail north to a board with a knot".
The photo that Daphne takes of the Morse code on the trail does not match the angle of her camera.
The McCoys and Hatfields are shown as living in the Ozark Mountains, which spread over Missouri, Arkansas, Oklahoma and a tiny bit of Kansas. The historically feuding families of these names lived in the Appalachian Mountains of West Virginia and Kentucky.
When the barn animals start eating the feast, it shows a donkey and a goat eating a bowl of sausages and a turkey, respectively. Donkeys and goats are normally herbivores.