Almost all of the cars seen have both front and back license plates. However, Arkansas does not require cars to have plates on the front and back of cars.
The case with the money had been submerged for several years but the money was bone dry.
Just before MacGyver, Jack, and Pepe enter the mine for the first time a man is wielding a pick axe on a pile of rocks, although he is barely hitting the rocks, if at all.
When the prisoners pull up to the mine in the truck large mountains can be seen in the background. There are no mountain ranges that look like that anywhere in Arkansas. However, there are mountains like that outside of Vancouver BC where the show was filmed.