After Polly steals the urn from her boyfriend's house, while she explains the theft to Malcolm in the car, her hands inexplicably change position around the tub.
When Hal shows Lois the hot tub he bought Reese is holding a tube of caulk but in the next scene his hands are empty.
Otto runs from the barn holding a 5 pronged hay fork aloft. It is struck by lightning and there is a flame on the tip of a prong. He falls to the ground and in the close up shot, the flame is at the bottom of a different prong.
When Otto's pitchfork gets hit by lightning, it an obvious double that falls backward to the ground.