The television set at the ranch is a modern model and much too small for that era. A model in the 1960s was much larger because it uses vacuum tubes which gave off a lot of heat. And when it was turned off a little white dot should have appeared on the screen which didn't happen.
In the scene with the two girls dancing on the hood of a car holding rifles, they are holding modern versions of AR-15s. They have collapsible stocks and were not the design of that era but of a much later modern version.