The Case of the Wayward Wife - S3-E13
Revealing mistake: Perry and Della step into an elevator but there is no line in the floor between the floor they are on and the elevator floor. It's continuous.
The Case of the Capricious Corpse - S6-E2
Revealing mistake: The murder victim is seen through the legs of a chair - just as the scene changes he blinks. (00:11:00)
The Case of the Sausalito Sunrise - S9-E19
Revealing mistake: Secretary Della Street answers the telephone in Perry's office and speaks briefly with the owner of an art gallery. She presses the "hold" button, then hands the receiver to Perry and says, "It's Mr. Clune." Perry and Mr. Clune have a lengthy phone conversation, even though Della never released the "hold" button.
The Case of the Sleepwalker's Niece - S1-E2
Revealing mistake: The carpets in the sleepwalker's house looked like they're unfolded tarps. There are noticeable folds in the carpet that looked as if a folded cloth had been unfolded but the creases were still there.
