Other mistake: When Midge is doing her skit for the soldiers she is pretending to read articles off a magazine. Yet instead of flipping the magazine, she is swiping as if reading off a smartphone.
Suggested correction: "Swiping" is not specific to smartphones or computer tablets. People often do this to speed through books, magazines, or documents, usually by slightly moistening the tip of the index finger, rather than individually turning pages. Midge is pantomiming her act, so her action is naturally a bit exaggerated for effect.
It's Comedy or Cabbage - S3-E5
Continuity mistake: When Midge descends the hotel's grand staircase, the piano player and guests are below. Once down the stairs, Midge finds Abe and Rose sitting in chairs with their luggage, just to the right of the piano, in front of a large pillar, with a round sofa behind. However, when Midge was walking down the stairs, the lobby looks different. The piano is in the same position relative to the stairs, but her parents and the chairs are missing and the round sofa is a different style and the shape of the carpeting in front of the pillar is also different.
