Barney Slater contributed only three scripts to season three of Lost in Space. These were “The Anti-Matter Man” (co-written with Robert Hamner), “The Flaming Planet,” and “Junkyard in Space,” the last first-run episode aired (“A Visit to Hades” from season two would be rebroadcast the week after “Junkyard” to round out the season in March 1968).
“The Anti-Matter Man” is a fan favourite and features Guy Williams and Mark Goddard throughout. The episode invites comparison with Slater’s earlier season one episode “Follow the Leader.” In both episodes, evil is overcome by love. In “Follow the Leader,” it is his son’s love that allows John to drive out the spirit of Canto that possesses him, and in “The Anti-Matter Man” it is Will’s love shown in rescuing his father that enables John to overcome his evil double in the climactic fight scene.
“The Flaming Plant” is an example of one of those episodes that could have been better if it had only tried. While Dr. Smith ignoring standing orders about taking plants into outer space is quite credible, the mutation of that plant caused by radiation (I shudder to think what the vegetable crisper in the Robinsons’ fridge contained) and the subsequent dangers it poses to the Jupiter 2 are a bit much. One also has to ask why Slater gave the Jupiter an intake vent (and what the vent was supposed to take in in the vacuum of outer space that made it vital to keep it clear). The interlude on the Sobram world would have made a very good episode on its own, but the resolution of the episode’s conflict is simply another example of Slater’s difficulty in coming up with plausible endings (although in this case it is certainly ingenious).
“Junkyard in Space” leaves the Robinsons marooned again after three years in space. Although it is not a fast-paced, or indeed even an adventurous episode, it does have some very good moments. At least that allows fans to overlook Slater’s assertion that the Robot’s love for Will kept him from being consumed in the blast furnace; touching as it is, it is nonsense from the point of view of physics.
Looking at Barney Slater’s scripts over all three seasons of Lost in Space, one might be justified in observing that their quality slipped as the show was retooled in season two and again in season three. Slater was most consistently at his best in his season one work.