Continuity mistake: Diamond is backing his convertible up to drive away from the crime scene. He turns to look behind him and places his right arm on the top of the seat. When the shot cuts to a wider angle, his arm is suddenly in a different position, draped all the way over the back of the seat.
Richard Diamond, Private Detective (1957)
1 continuity mistake in One Dead Cat
Starring: David Janssen
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.