Re: most "wrong" episode...
To me there are a few TOS episodes. Omega Glory comes to mind. The savage "Yangs" (who are white) that love freedom and the "Kohms" (of Asian descent) are oppressed.
I'm not sure that was the intent, more about giving the audience something they easily recognize.
"...the most elementary and valuable statement in science, the beginning of wisdom, is I do not know." - Lt. Commander Data, "Where Silence Has Lease"