When Will Robinson is repairing the robot he puts the power pack on, then reconnects the robot's head, then (after a jump cut) he puts the power pack on again.
Looking at the robot's right claw at 34 minutes, the top inner side of the claw has 2 holes in it (probably used earlier when he was holding a pointer while teaching the children). But moments later no holes are present suggesting a 2nd robot is being used.
When the bowling ball bomb is rolled back towards Will, Dr Smith and the Robot, it comes to rest a few inches away from a bolder, but in the next camera shot is a couple of feet away.
A standard-size bowling ball of solid gold would weigh about 225 lb. It's unlikely that young Will would be able to pick up/carry such weight easily as shown.
The reflection of three studio lights are visible in the bowling balls.