In certain respects this episode seems like a complete disconnect from the previous two episodes of the 3rd. season. Significantly, the writers of Lost In Space did not include an episode in which the Robinsons struggle to return to their own time after taking off from Earth in 1947. That would have been a very exciting episode for the writers to include, and provided powerful series continuity like that of the 1st. five episodes of the 1st. season. The most striking aspect of this episode is the premiere appearance of the Space Pod, and the question evoked on the part of LIS fans: Where was the Space Pod for the previous two seasons of Lost In Space, especially in the episode 'Island in the Sky'?
One possible theory:
When the Robinsons went back to Earth in 1947, they affected the course of history. When they returned to the present ( presumably they returned to the present ) it was now to an altered timeline. In the unaltered timeline, the Space Pod did not exist ( note that the Space Pod Bay had previously been a storage room, as seen in the episode 'The Mechanical Men'). Now it suddenly did exist. Also when the Jupiter 2 encounters the Xenian space probe (which looks exactly like the derelict spaceship encountered in the 1st. season), Prof. Robinson remarks: "I've never seen a spaceship that big in my life." It's possible that in the altered timeline, the Robinsons never did encounter the derelict ship, thus Prof. Robinson's comment. Also suggesting an altered timeline: In this episode it is made obvious that prior to the Jupiter 2 expedition, the Robot had been a sentient, self-determining entity, rather than the comparatively mindless automaton seen in the first few episodes of the 1st. season. We learn that he majored in medical science ( or something like that), but then decided he was more interested in space exploration. Later in the 3rd. season in 'The Antimatter Man', the Robot tells Will that friendship was one of the first virtues programmed into him, further suggesting that he had been designed as something more than just a machine by Alpha Control. Also, the Bloop, who was seen in the first two of the 3rd. season episodes, is conspicuously absent in this episode and for the remainder of the 3rd. season.