Continuity mistake: While Diamond talks to the newspaper editor, he has two locks of hair falling over his forehead in full shots, but in close-up, his hair is neatly combed back. The forelocks come and go repeatedly after that, throughout the episode. (00:18:00)
Richard Diamond, Private Detective (1957)
1 continuity mistake in The Dark Horse - chronological order
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.