Early on in the film, Zoe is seen using a smartphone. Later in the library scene, she is seen using a flip phone.
Just after the opening scene, when Mick Branson is driving out of town and then arriving at the trailer house, the lawnmowers change positions. While in town the handles are pointing toward the passenger side of the truck, but when he stops at the trailer house, they are pointing toward the back.
The rifle is a bolt-action, requiring a manipulation of the mechanism for each shot, which takes from about one half second to two seconds, depending on the Operator. When shooting at the Driver on the dirt road at the Ranch, the sound of the reports are in semi automatic, rapid fire timing, which isn't possible with a bolt action, even if by Lee Oswald.