
Visible crew/equipment: When Father Mulcahy and the farmer are talking to BJ and Hawkeye about the wounded cow, the doctors say they'll get help from Colonel Potter, and when they walk away the T-mark can be seen on the ground where they were standing.
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 ★