- Narm Charm: Leonard Nimoy riding high on his success in Star Trek, rocking the 70's 'stache, delivering a completely serious and compelling narration of mysteries ranging from the topical, to the unheard of, to the completely ridiculous. And it is wonderful to watch.
- Nightmare Fuel: The series had a music score that when combined with Nimoy's voice was enough to guarantee nightmares, especially when the episode is about nightmares.
- The screaming skull.
- The profile on Carlos the Jackal, to a child in the 1970s watching this show that dealt with ghosts, monsters and the like, the inclusion of this real life cold blooded killer terrorist felt terrifying as a real threat, only mitigated slightly by the footage at the end of commandoes training to fight him.
- The loving description of a theoretical 1906-level earthquake in modern Los Angeles in the "Earthquakes" episode.
- Nostalgia Filter
- Sequelitis: An attempt was made to revive the series in 2002 with Mitch Pileggi as the narrator, and it lasted for 8 episodes.
- Unfortunate Implications: In an episode concerning the Dead Sea Scrolls, the narrator refers to Israel pushing Jordan out of the west bank during the Six Day War as a blitzkrieg.