The hallway area outside Butch and Kent's cell changes between scenes, possibly due to reshoots (see Trivia).
The position of Butch's head changes in relation to the wall in the letter sequence with Morris.
When Butch smacks Kent in the cell, Kent falls face down. When Butch picks him up, the unconscious Kent is face up.
Butch and Morgan spend 30 days in the dungeon, but when they come out, their hair and beards have barely grown - at most, a week's worth; definitely not 30 days' growth.
As Butch puts Kent into the top bunk, the unconscious Kent bends each leg slightly to avoid hitting the pole holding up the corner of the bed.
When Anne comes to visit Kent at the prison and he walks up and says, "Hello, sis", the shadow of the microphone falls across her.