Continuity mistake: When Preacher is about to kill Stockburn, as he walks toward Stockburn he reloads his revolver by replacing the cylinder. He briefly points the pistol at the camera, you should be able to see bullets in the chambers of the cylinder but they are empty. Again, just before Preacher actually shoots Stockburn, he points the revolver at the camera and you see empty chambers where you should see the unfired bullets.
Continuity mistake: When the preacher stops La Hood's son Josh from raping Megan, he shoots Josh's revolver from his hand, then shoots his hand, then shoots the revolver away from Josh with two more bullets. In the next shot where Josh rolls away, the revolver is back in its original position.