Don uses the "jet pack" to go look for Will and Dr. Smith. In the wide shots, he is wearing a dark jacket, yet in the close-ups Don is wearing a medium-colored jacket. BTW, this same thing happened with Don in an earlier episode.
The "life raft" being used is the Jupiter 2's reaction chamber since it is airtight and can be sealed against the vacuum of space. However, it's too massive a piece of equipment for two men to have extracted from the spacecraft without heavy lifting equipment, and there's no apparent way to have gotten it outside from the lower deck which is buried in the ground. Also, this chamber would seem to be a vital component to the Jupiter 2 if the crew had any hopes of returning to space.
The balloon attached to Will's message rocket is too small to lift a metal object of that size, an error repeated with the balloon attached to the reaction chamber capsule; its balloon is also too small.
The "Power" meter used to test the engines of the Jupiter 2 is actually a relabelled automotive dwell tachometer. In the close up at around 15 minutes, calibrations for 4 cyl, 6cyl and 8 cyl can be seen on the face of the meter.
When Maureen & John are seen searching for Will in the Chariot, with Maureen driving, this is a actually footage from Invaders from the Fifth Dimension (1965), even with some of the dialogue where John says to Maureen, "Let me drive for awhile." being identical. Long shots of Don with the jet pack are also previously used footage.
Early in the show, as the Robot is standing by to release another of Will's experiments, "fishing line" can be seen above the balloon prior to the experiment's "launch."
Prof. Robinson implies that energy plasma and blood plasma are similar, when in fact they have nothing in common.
John Robinson mispronounces "Procyon". Procyon, aka Alpha Canis Minoris, is about 11.5 light years from Earth. If they can locate Procyon from the location of the Jupiter II, they should be able to find other nearby stars and calculate the Solar System's position, meaning that they're not really lost in space.
But John Robinson does say 'IF' it is Procyon, so, they won't know until they are already on their way.