Revealing mistake: When "Selden" falls down the stairs it is obvious that it's a stunt double.
The Twilight Zone (1959)
1 revealing mistake in Nightmare as a Child - chronological order
Stopover in a Quiet Town - S5-E30
Visible crew/equipment: When the camera pans to Rod Serling for his opening narration, you can very briefly see several crewmembers and some backstage equipment.
[A bomb in Wadsworth's room is seconds from going off, causing the Chancellor to panic].
Chancellor: Please, please let me out. In the name of God, let me out. Let me out! Let me out!
Wadsworth: Yes, Chancellor. In the name of God, I will let you out.
Trivia: Producer William Froug rejected an extremely nervous young singer/actress auditioning for the part of Mary Rachel, and recalls thinking that "I'll probably kick myself. She'll probably be a big star." He turned out to be right on both counts. The aspiring young singer's name was Liza Minnelli.
Question: Who portrayed the female 'new model' alongside the male 'new model' (Edson Stroll)? She did not have a speaking part.