Character mistake: Or continuity: When Ricky enters the Mertz's apartment, waking everyone up, little Ricky starts crying in the crib, and Ricky moves closer and accidentally says, 'Why is she awake?' instead of 'he,' as his own baby daughter Lucie was almost 2 at the time.
Suggested correction: The issue was due to his accent; several times during the course of the show, when Rickey said "he," it sounded like "she."
Visible crew/equipment: After Lucy and Mr. Beecher sign the lease, just as they all start heading toward the door, the taped T-mark is visible at the bottom of the screen at the edge of the carpet (presumably for the second camera dolly offscreen at the left). Then as Mrs. Hammond walks out, a bit of overhead set equipment can be seen at the top right side of the screen. (00:12:45)
Visible crew/equipment: While Ethel and Lucy are trying to frighten Mr. Beecher so he'll leave the apartment, when Lucy blows up the balloon the reflections of all the overhead set lights are visible on the balloon. (00:23:00)