Sometimes You Hear the Bullet - S1-E17
Continuity mistake: Hawkeye lifts Wendell's arm, takes his pulse and lays his arm down by his side again. In the next shot, Wendell's arm is across his chest. (00:13:55)
Sometimes You Hear the Bullet - S1-E17
Continuity mistake: As Frank receives his purple heart, Henry calls him 'Franklin D. Burns' All other references to his full name in the series give his middle name as 'Marion'. (00:23:50)

Sometimes You Hear the Bullet - S1-E17
Continuity mistake: Frank and Margaret are dancing in her tent when Frank's back seizes up; in the subsequent shots sometimes his arms are around her waist and sometimes around her shoulders. (00:02:30)
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 ★