April Fools - S8-E25
Other mistake: When Charles, BJ and Hawkeye steal Margret's tent, what's left is a frame of wood, including roof beams. From other episodes we know that the tents are held up by a wooden frame around the edges and a center pole. We even know for a fact that Margret's tent is built that way, because in an earlier episode Hawkeye and Trapper saw through the center pole of Margret's tent. We also know that the construction principle of the tents hasn't fundamentally changed since then, because when Hawkeye finds the oatmeal in his boot earlier in the same episode, you can see the center pole of the Swamp.
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 ★