Continuity mistake: Diamond returns to the all-night cafe and parks with his car pointing toward the door. After he goes in and comes back out, the car is in a completely different position, parked parallel. (00:10:20 - 00:11:30)
Richard Diamond, Private Detective (1957)
1 continuity mistake in A Cup of Black Coffee
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.