Helen's Job - S2-E13
Visible crew/equipment: Janet stops Helen from leaving, says she can't handle seeing her beat. After Helen's speech about winning the war, as the camera zooms out, a piece of set equipment is briefly visible at the top of the screen. (00:16:55)
Helen's Job - S2-E13
Factual error: After Mr. Roper stirs Jack's batter, Jack pours it into the cake pan and then opens the oven, leaving plenty of batter residue inside the mixing bowl, which a professional chef student would never do.
Answer: I believe you are referring to the artwork of Alphonse Mucha. On the wall next to the front door was "Feather" (which is one half of "Primrose and Feather"). Above the telephone in early episodes was "Zodiac". Also seen through The Apartment was "Spring" and "Autumn".