Visible crew/equipment: While Kilnger's guarding Soon-Lee, when Father Mulcahy walks into the tent the shadow of the boom mic dips into view at the top, left side of the screen.
Visible crew/equipment: In the Swamp, when Houlihan shouts, "I'll be back and you better come up with something," the moving shadow of the boom mic can be seen at the top, left side of the screen.
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 ★