That would be pretty interesting. I dunno, maybe put an egg in there instead of the poison vial, creating a superposed system of intact egg/cracked egg instead?
But the whole point is that such a superposition is never observable. Any way of detecting it would cause it to collapse into one specified state. The only way to distinguish it from a non-quantum system is that it can be linked statistically to another quantum system. And even then, you're still only going to observe the same set of outcomes you'd see otherwise. The quantum part affects only the distribution of those outcomes.
