Plot hole: When Hawkeye wrecks his jeep on his way back from an aid station, he has a Korean girl take a message to the 4077th, which he claims is 20 miles south. However, in virtually every episode, it is claimed that the 4077th is located 4 miles from the front lines.
Plot hole: When the truck with the orphans arrives, Col. Potter and Nurse Cratty greet each other like one would an old friend. Being new to Korea, Col. Potter doesn't know Nurse Cratty - as becomes clear from his reaction to Hawkeye's explanation to BJ earlier (who doesn't know Nurse Cratty for the same reason, but that's not relevant for this mistake). Note that in other parts of the series Col. Potter is depicted mostly as somewhat old-fashioned and reserved towards strangers.