This is the first appearance of the Zarn, possibly the most memorable character from the Land of the Lost. At the time this episode premiered, I am sure it probably freaked some of the younger viewers out a little. Zarn and his ship made of lights make for quite an unusual sight.
We see one of the coolest set pieces, the Mist Marsh, for the first time. All the fog and dead trees combine with the open spaces to create an aura of mystery, leaving the audience guessing as to what lies ahead. The dialogue throughout much of the show seems to be kept short, helping increase the emotional tension and atmosphere. In the marsh, Will tells Rick that he feels as if someone or something is picking through his brain, reading his mind. This increases a sense of dread as they enter the Zarn's spaceship, one of the most visually unique experiences in the Land of the Lost. It basically looks like a fun house full of invisible walls, with light bulbs outlining the edges of everything. For the mid 70s, that must have been really cool to see.
Rick and Will meet a peculiar woman, who the audience knows right from the get-go is not exactly normal, but the Marshalls only slowly start to realize that. When the Zarn makes a night-time appearance outside High Bluff to bring the woman back to his ship, the audience is left wondering what exactly is going on - Is the woman, or Zarn, friend or foe? After Rick follows her back to the Zarn's ship, we learn what the woman is, but even after a confrontation with the Zarn, we are all left wondering if Zarn is more of a villain, a jokester, or a neutral character.
All in all a classic episode.