Revealing mistake: In the supply room, as Hawkeye lights two candles, the room gets noticeably brighter. However, there's too much light for two candles, and his shadow comes from above.
Revealing mistake: In the closing scene, as the camera looks at the collected crowd, the camo net over the building poorly hides the edge of the "sky" background and the sound stage walls.
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 ★