Continuity mistake: When Jack delivers the patient to the MASH and when he is taking photos of the operation, there is no wound on his right hand. It only appears when Col.Potter says that he treated it "months ago". (00:04:30)
Continuity mistake: After Jack wins a drink from Hawkeye and BJ, Hawkeye grabs the orange to inspect it for tears to prove his magnet theory. After the angle change, he grabs it again.
Answer: The C-42 was a military variant of the Douglas DC-2. Very few C-42's were built, so it's questionable that Potter would specifically have seen that particular model, but, given his military background, it's not entirely unreasonable that he might use the military designation even when the aircraft in question is actually a civilian DC-2.
Tailkinker ★