Thanks to Yet Another Hot Question List Ignorance Incident, we have a question with an answer that is 100% wrong and contradicted by canon, yet upvoted to 50+ upvotes.
So far, I posted a correct answer, asked the OP to consider changing their "Accept", and posted a comment under an incorrect answer.
However, (barring the OP changing their accept mark), that seems well-nigh useless: nobody will read a comment under a long answer with 50+ upvotes to check if that answer is correct; and nobody will pay any attention to an answer with a couple of upvotes when the accepted one has 50+. And the "normal" self-correction mechanism of SE site won't work here, since there will be no flood of ~4000 viewers to provide enough upvotes for the correct answer to even remotely catch up, even in several years.
Would it be an acceptable thing, to edit in a disclaimer note at the START of the answer, that the answer is canonically wrong, and opposite of what the correct answer is?