Visible crew/equipment: After Harper, the JAG, has Trapper and Hawkeye sign and attest to the blood report, when Radar enters Henry's office we can see a crewmember's hand near the floor between the two doors, preventing the closing door from swinging back and forth. (00:22:20)
Visible crew/equipment: While Radar is in Henry's office with the woman and her baby, being teased by Trapper and Hawkeye about the possibility of him being the father, just as Frank walks into the office a crewmember's hand can be seen between the two doors near the floor, preventing the closing door from swinging.
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 ★