When Will and Dr Smith first find the enlarged-size Robot in the Valley Of Shadows, a wide-angle shot of the Robot shows his full size. However, Will and Dr Smith walk around inside of the Robot like his size is much, much larger.
When Will and Dr Smith first take off the panel on the bottom of the Robot's treads to climb inside, there is a tread shown only to the right of the opening. When Professor Robinson and Major West first encounter the larger-than-normal size robot, treads are shown on both the left and right of the opening.
When Professor Robinson and Major West first encounter the much-larger Robot in the Valley Of Shadows, there is nothing lying on the ground to the right of the hole in the bottom of the Robot's tread. When they walk up to the hole and the camera shot changes, there is a log lying to the right of the hole.
When Professor Robinson and Don first encounter the larger-than-normal Robot in the Valley Of Shadows, the hole in the bottom of the Robot's tread that Will and Dr Smith went through is dark. When they walk up to the hole and the camera shot changes, the hole is suddenly white/bright.
When Professor Robinson and West arrive at the giant robot the screws on the plate removed by Will are now in different positions.
When the robot begins to shrink back to normal size, none of his internal parts are actually getting smaller as Will and Dr. Smith are trying to get out, they are only getting closer together while staying the same size.
While inside the enlarged robot, a number of things have not actually enlarged such as: an IBM style tape driven computer, other spinning reels, various lights and switches, the large circuit board that Will is working on, etc. Also Will would not have been able to work on any of the equipment inside the computer as he has a standard size toolbox and tools. The tools he would have needed would have been gigantic and possibly difficult for him to handle.
Some of the mechanisms inside the robot contain control panels, but if the robot were its normal size, no one's fingers would be small enough to work those controls.
The red light on top of the internal laser protective device is a police car dome light. This would have been available on police cars in the sixties and maybe 70s, but by 1997 when the Jupiter 2 departed, a light bar across the full width of the police car would have been standard equipment.
When Penny was playing the tape of the robot's message, there was just a loop of tape running around the reels (like a belt) not contacting the play head, and could not possibly been able to produce any sound.
After the reversal process begins not only does the Robot starts to shrink, but the metal panel Will removed does too. The metal panel (which had been separated from the Robot's body) should have remained at the enlarged size.