When Beth and Wally are travelling in the convertible, the scenery in the shots from the front of the car does not match with the scenery in the shots from the sides of the car. It changes from fields to forest and back again.
Food Lion was referenced twice in Uncle Frank. The grocery store chain Food Lion did not come into being until 1983, and was not in existence 1973.
As someone else mentioned, the name FoodLion came in the early 1980s. In the 1970s, the grocery store chain was called FoodTown.
The boy that was found in the lake by Frank, wasn't the boy that he was about to have relations with that Daddy Mac had witnessed.
In one scene with Walid and Beth talking at the kitchen table there is clearly an iphone in Walids's front pant's pocket. When they cut back it is gone.