Revealing mistake: After Book shoots McFee, McFee is leaning against the wall with a shotgun in his hand. He is holding a full pump action shotgun with one hand pointed up while wounded and then fires the gun. When he does, there is absolutely no kick to the shotgun at all, revealing it to be a blank shot.
Deliberate mistake: To keep things simple, the movie relies on the Lancaster County Sheriff as a county police force. In reality, the county sheriff serves the county court (transporting prisoners, for example) but does not serve as a county wide police force. In PA, each city, borough, and township has its own police force. Note the varied colors of police cars at the farm in one of the final scenes. These were borrowed from the various local police forces (Lancaster City, for example, is robin egg blue with a white top).
Character mistake: Locals pronounce Lancaster as LANGkaster. It is commonly mispronounced "Lankaster." When Shaeffer first calls the local police, the sergeant first pronounces Lancaster correctly but incorrectly later in the call.
