Never Do Business With Friends - S2-E32
Continuity mistake: In Lucy and Ricky's apartment there are six shutters between the kitchen and living room, a set of three open to the left and three open to the right, but after the washing machine falls off the porch, when Mrs. Trumble's nephew thinks they're all crazy he runs through the back door and we see a set of four shutters on one side. Also note the round knobs are at the bottom corners, when they should be higher up at the center. (The prop shutters that we see through the doorway during the porch's "exterior" shots are identical to the seven shutters that were in apartment 4A, before the Ricardos moved downstairs). (00:22:10 - 00:24:25)