Plot hole: When Oliver attempts to lift the drain grille in order to get the drunk's car key, he claims it is too heavy. Yet when Stan gets his umbrella stuck down there, Oliver manages to lift the grille without any effort.
Continuity mistake: When Stan and Oliver are in the bedroom of the judge's house, Stan is lying on the bed and you can see the cigar in his mouth is already lit. But a couple of seconds later, he is lighting the cigar.
Continuity mistake: When Arthur Houseman takes out the water from the jug and replaces it with gin, you can see there are two glasses in front of the jug, but when we see him pouring gin into the jug in the next shot, the glasses have changed position.