There's nothing Mighty about this little green flapping feet robot - the one on the left. It exists in enormous quantities and forms the start of many collections.

The basic green body has litho detailing, a red plastic spark panel (not the usual Noguchi 'Lego' panel), and flapping feet. There was a later issue of this robot with plastic feet.

There are some rarer versions of the Mighty Robot, these have distinct legs and feet ('split leg'). There are green and silver litho versions..

Split leg.

Later version, blue litho and plastic feet and key.

The Koreans (S.U.) reissued the little Mighty Robot with metallic blue litho and plastic flapping feet. These are considered to be rarer.