Continuity mistake: The hot knives that are set up in the King Lear scene towards the end of the film are sometimes smoking and sometimes not depending on the shot.
Continuity mistake: Near the end when Howie is in the cage and praying, one shot shifts to the line of watching islanders. Summerisle walks towards them, turns and signals with his left arm. Cut back to Howie in the cage, then back to the islanders. The same sequence of Summerisle walking and signalling is then shown again.
Continuity mistake: Shortly before Sol's death, Thorn rushes into the suicide center and talks to him from the control room above. When Sol pleads Thorn to listen, there's interference on the intercom. Now watch the control panel: The earphone cable on the left side dangles back and forth each time the "speaking permitted" sign flashes on and off, blatantly revealing the cheap trick they used to make the display flashing - they simply toggled the "on" and "off" frames. (01:17:30)