Revealing mistake: This episode's futuristic video-phones seem to be a production afterthought not in the original script. Consequently, Mrs. James talks to her husband's clone on the phone, but doesn't seem to see him on the screen. She tells James, "He sounded like you," and goes on about his voice, but never mentions his appearance. Later, her reaction to seeing both of them together indicates she's never seen the duplicate before - even though she has, on the video-phone. (00:25:00)
The Outer Limits (1963)
1 revealing mistake in The Duplicate Man - chronological order
Continuity mistake: When the lab equipment shorts out after the earthquake, the unconscious Major Brothers is lying with his head propped up against the wall. But when Hamilton reaches him in the next shot, he's suddenly lying flat and is nowhere near the wall. (00:21:45)
Andro: Better to die than to sit and watch the world die.
The Forms of Things Unknown - S1-E32
Trivia: Part of Dominic Frontiere's haunting musical score for this episode later became the theme and background music for the TV series The Invaders, a show for which Frontiere served as the primary composer.