The Case of the Cheating Chancellor - S9-E4
Character mistake: Paul Drake tells Perry the "speedometer mileage" of a murdered man's automobile is 63,192. Speedometers do not show mileage. He meant to say "odometer."
Perry Mason (1957)
1 character mistake in The Case of the Cheating Chancellor
Starring: Raymond Burr, Barbara Hale, Ray Collins, William Hopper
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.
Hamilton Burger: Incompetent, irrelevant, and immaterial.