Stupidity: Wouldn't it be common sense to have more than one remote to control Robo-Cain? That way, if he destroyed one (and he did), they could still use one to shut him down from a distance (as long as they can dodge the gunfire).
Stupidity: Dr Faxx knew full well that Nuke was Cain's greatest weakness, but it never occurred to her to mention to the old man that holding a canister of it in front of him during the exhibition could have serious consequences. Not very bright.