The Saticons lower the temperature in the space ship, hoping it will be fatal to the humans inside. If that were possible, the ship would not be able to travel in the vacuum of space where the temperature is -459 degrees F.
At one point, Penny tells Archon that the temperature in the Jupiter II is 10 below zero, yet she has her coat unfastened, and there are no vapors of frost coming from anyone's mouths or noses.
As with the castaways on Gilligan's Island, the Robinsons quite often have a number of costumes and props that they couldn't possibly have brought along with them when they left earth (such as those that Penny, Will, and Dr. Smith are using for the play they are performing.).
When Arcon explains that the evil "Saticons" are about to arrive, no-one seems to know who they are. However, the Saticons had already visited the Robinsons in Wreck of the Robot (1966).
Penny states that the temperature has stopped falling. The device she uses to determine that is clearly labeled "barometer" which measure atmospheric pressure, not temperature.