I think the most intriguing scene in this whole film is when we find out that Robby the Robot is really SUPPOSED to be the same one constructed by Dr. Edward Morbius on Altair-4 (in the movie Forbidden Planet). Supposedly, at the end of that movie, the United Planets' StarCruiser C-57D returns to earth with Robby the Robot and Altaira Morbius. Somehow, a professor from the 20th century travels forward in time to the 24th century in a time machine, witnesses the landing of the C-57D StarCruiser at Chicago Spaceport, takes a black and white photo of it, then somehow persuades Robby to come back with him to the 20th century. The robot then somehow ends up being dismantled and (in the movie The Invisible Boy) we find him lying in pieces covered with dust on a shelf. The boy Timmie (with the help of computer induced hypnotic instruction) then reassembles Robby.
Quite an ingenious plot device, tying the two movies together.
Quite an ingenious plot device, tying the two movies together.