Oil for the Lamps of Hogan - S1-E14
Other mistake: Anytime Hogan steals one of Klink's cigars from the back of the humidor, he takes the hinge pin out from the left of the box (camera's right). This time, he takes out the pin, got the cigar, and put the pin back in from just what looked like just left (camera's right) of center.
Oil for the Lamps of Hogan - S1-E14
Continuity mistake: Toward the end, Klink removes his monocle while talking to Hogan about the oil. Through the next few cuts between them, the monocle is off. When Hogan goes to leave, there is a shot from behind Klink, and he doesn't move, yet the next closeup of Klink shows the monocle in place.
Oil for the Lamps of Hogan - S1-E14
Plot hole: The Heroes take an empty oil drum to the depot, knowing full well that Schulz will protest, allowing them to steal a full one. However, all but their barrel have snow on it. Since it's really salt, it all falls off as they load it on the cart. With real snow, that wouldn't happen. It would be quite obvious that the barrel they are taking out is not the one they brought in.
Answer: It's a solitary cell. Steve McQueen, star of 'The Great Escape' is known as the 'Cooler King'.