Revealing mistake: The car that goes over the cliff is at least ten years older than the car it's supposed to be - the 1957 Plymouth Fury that Diamond was driving. It's obviously old 1940s stock footage.
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.