What ethical issues, if any, are raised by plato's allegory?

Plato's allegory of the cave raises a number of ethical issues:
... Do we have a responsibility to search after truth rather than simply accept common opinion?
... If we have greater insight or access to truth than our peers, ought we try to enlighten them with the knowledge we have gained?  What if they prefer to remain "in the cave," seeing life the way they already see it?
... What are the obligations of a society toward someone who tries to push them toward new understandings or new perspectives?

We could relate the whole allegory of the cave, but you already are aware of it if you're asking the question.  One can see something of the story of Socrates, Plato's mentor, in the cave allegory.  Socrates had sought higher truth, more than just opinions and shadows and images.  He felt that searching after truth was the only ethical form of life, saying, "The unexamined life is not worth living."  He also felt a duty to act as a gadfly (his term) to provoke others in Athenian society to search after knowledge along with him.  But Athens voted to condemn him, and under their laws he faced execution.  (Well, he could have escaped or offered a bribe, but he considered all such maneuvers unethical.)  So Plato's story has something of an ethical critique against Athens in it, that they turned against a man who was profoundly ethical and was urging them to seek truth as he did.