The Luck of Newton Monroe - S5-E29
Corrected entry: Newton Monroe, played by Don Rickles, is mopping the floor of the sheriff's office. As he moves the mop around, the mop handle breaks the glass on a bookcase and he freezes, embarrassed. In the very next shot, as Barney Fife (off-camera) is yelling at him, Newton is standing with his hands on his hips and the mop has disappeared.
Correction: The mop has not disappeared, it is in the very bottom left hand corner of the screen, stuck in the bookcase, as Newton puts his hands on his hip.