When the Guns Come Out - S3-E6
Plot hole: Raylan has a hunch that Winona took the money again from the evidence room, so checks the locker, finds the empty box, and assumes she stole it. When they returned the money in the previous season, he said "Put it back anywhere except for where you found it", so as to make it easier for someone to assume it had been misplaced, rather than lost. So the locker being empty is hardly a smoking gun for him to assume Winona's taken the cash.