As You Were - S2-E20
Revealing mistake: At the end, in the shot of Klinger singing while he's sewing a dress on his White Rotary sewing machine, as he's guiding the fabric forward it isn't actually under the machine's presser foot, which it needs to be in order to be stitched by the needle.
As You Were - S2-E20
Revealing mistake: As Henry goes over to the expectant mother, a round takes out the generator. After the lights go out, there is a blue light outside the window, and also blue lights over the action. They can be seen in the reflections on the light sets over the tables.
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 ★