Continuity mistake: When Henry, Trapper, and Hawkeye get into the jeep with Radar notice the style of jeep and its number is 16930382, but when they're driving to the chopper pad the style differs - things such as hood, antenna, etc, and its number is 11172419. Then when the chopper takes off the jeep's style is back to the original jeep they were in.
Continuity mistake: As Henry watches the chopper fly off, his back is to Radar's jeep. After he orders back to camp, Henry is suddenly standing with his right side to the jeep without having turned.
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 ★