When the Jupiter 2 lands on the alien planet, two crew members (likely Don West and Professor Robinson, since the others were given instructions to strap into the space couches) are shown standing by the main window in the space ship. When the camera switches to an interior view, Don West and Professor Robinson are shown in their seats as they begin to unbuckle.
When the robot is initially shot by the alien after being sent outside to test atmospheric conditions, he is rendered helpless. His position as seen from the main window of the Jupiter 2 is in front of Gate 115, angled a little to the right and under the letter "E." When seen the next morning, his position is further to the left of camera, under the letter "G" and now angled to the left, when viewed from the same window in the Jupiter 2.
After the robot is shot by one of the aliens and rendered inoperable, his arms and body can be seen moving when the aliens come through Gate 115.
When Smith returns to the treasure room & is surprised by the alien robot he puts his right hand up to his chest & his left on the rock beside him. In the next shot his left hand is on his chest with the right near his waist.
The components (that Dr. Smith labors upon in the factory) pile up at the end of the conveyor belt rather than drop into the bucket. After a commercial break, the pileup has been merely removed for the next scene.
At 37:20 the dolly that is pulling the robot across the dry ice is clearly visible.
The Jupiter 2 radar display is very pretty but absolutely impractical, showing no changes whatsoever against changing situations.
John is so impossibly tough, and his mechanized foes so fragile, that he can disable cybernetic foot soldiers with a single karate chop to their metallic guts.
As the camera zooms in on Dr. Smith at 16:00, the shadow of a boom mic can be seen sliding across the ceiling beams in the background.
Will says the outside temperature is "1,000,000º K [degrees Kelvin]." Not only is that temperature much too high for the ship to survive (hotter than the surface of the our sun), degrees are not used with the Kelvin scale. He should have only said, "one million K."
When Maj. West and Prof. Robinson attempt to regain control of their space ship, West calls Robinson "Guy" rather than his character name "John."
Smith tells the Robinsons that an evening banquet is being prepared & that cocktails will be served at 0500. 0500 is 5 o'clock in the morning. He should have said 1700 for the evening.