Continuity: When Harry Morgan is sitting in the bar, the bottle on his table moves around and disappears between shots.
Continuity: When Frenchy takes Capt Morgan to the cellar to remove a bullet, Frenchy unlocks the cellar door and promptly relocks it after they enter the cellar. A few minutes later, Slim comes down the stairs in the cellar with the first aid kit and the hot water. Frenchy has been in the room with the wounded man all this time and couldn't have unlocked the cellar door.
Revealing mistakes: When Morgan throws water at Eddie, the bucket is obviously empty - noticeable both in the way it's handled, and in a momentary glimpse of the insides before the camera cuts to Eddie.