When both boys use paint at the director's place, the gallon of paint besides Turner labeled Rebel Green is listed both as 1 gallon and 3.. liters. As that scene takes place in the 60s, it's at least an oddity. Would both listings be written then? In Canada, conversion to metric system came into effect in the 70s.
Early in the movie, when MLK is shown on various TV screens in the window of a store, you can see the camera's reflection in the bottom left of the screen.