Continuity mistake: When Robert Blake and his accomplice take the father and son to the basement, Blake pulls the string on a hanging lamp and the room becomes fairly bright. A moment later, Blake's accomplice pushes the father into the same room, which is now significantly less well lit, even though the same hanging light is still on.
In Cold Blood (1967)
1 continuity mistake - chronological order
Directed by: Richard Brooks
Starring: John Forsythe, Robert Blake, Scott Wilson, Paul Stewart
Factual error: In the scene when the two criminals are in the hardware store, two vehicles are parked outside that are clearly late 1960's automobiles, despite the film being set in 1959. (00:15:25)
Perry: It's true! Really true! We're on our way and never coming back. Never! And no regrets.
Dick: For you. You're leaving nothing. What about my old man... and my mother? They'll still be there when my checks start bouncing.
Perry: It's nice the way you think about your folks.
Dick: Yeah! I'm a real thoughtful bastard.