Revealing mistake: When the tent roof caves in and the projector shorts out in a gush of water from above, you can see that actually the projector "shorts out" before the tent roof ruptures. The crew probably didn't want to risk the pyrotechnic devices getting wet. (00:02:25)
Continuity mistake: During the scene which culminates in Frank declaring the camp dry the patches of water on his helmet change position. (00:05:50)
Continuity mistake: When Trapper turns around to ask Klinger for the status about the movie's sound, a small patch of his hat becomes wet from the roof's leaking, but in the next shot, his whole hat is instantly soaked. (00:01:55)
Factual error: During the Hawkeye and Trapper argument in the tent, Trapper seems to wearing a 70s digital LED watch which didn't exist at the time of the Korean war.
Visible crew/equipment: When Trapper and Hawkeye are in the Swamp they start arguing, and just as Hawkeye grabs the mandolin the edge of the Swamp set can be seen at the top, left corner of the screen.
Continuity mistake: When Father Mulcahy's finishing up his Sunday service with only Klinger, who's wearing a fetching red hat, there are nine stacked books at the corner of the table, but when it cuts to Mulcahy's closeup there are now only six stacked books (which will soon be used for the 11:00 Protestant service when Trapper and Hawkeye will pray for booze).
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 ★