The Accles & Shelvoke captive bolt pistol used to kill the pig was invented in 1903. Though the movie does not specify what year it is, the voice-over talks about 'the old century ', which means the epilogue is probably set in the 20th century and the rest in the three decades before.
The inflamed reverend falls through the window when Liz shoots him. In the exterior shot there's nothing burning outside the cabin. (This could have been done deliberately for reasons explained in Trivia)