[Steve_Alaniz]

OK the remote control in question was the Zenith Space Command... an ultrasonic system as was mentioned before, also called, the "clicker". There are a few available on E-Bay... But there is not a receiver unless you can find an old Zenith TV and gut it for the control part (which would probably use vacuum tubes so good luck!) . Or if you are an electronics Demi-god built your own. Probably very do-able for the mad Scientist types out there.
Everything else appears to be a single command item like the "Clapper"...
It's a great idea, but certainly beyond anything I would want to do. Ironically, I think I used to own one of these sets and even had the schematics but have long ago disposed of the schematics and the set. ( I always thought the Smurfs were green ... THAT's why I got rid of the set!)

Best of Luck

Steve