I disagree. I think there are three:
1- I think the Book of Abraham is a smoking gun, as does everyone who has ever looked into it who didn't already have a testimony of the church. He claimed to have actually, literally translated a document written by Abraham "in his own hand." It fails on every possible test, and it leaves no room to suggest that "translation" doesn't mean translation.
2- The recent discovery of Joseph's plagiarism of Adam Clarke's Bible Commentary in the "inspired" translation of the Bible appears to be emitting a dense trail of smoke too. Joseph never claimed to be collecting the comments of other commentators, he claimed to be re-translating the Bible by the gift and power of God.
3- The changes made to Book of Commandments revelations before they reappeared in the Doctrine and Covenants. Here we have Joseph changing the actual words of Jesus Christ, often to significantly modify their meaning as fit Joseph's needs at the time. These precious words or divine revelation, revealed finally to mankind after a centuries-long darkness. And Joseph just changes them as he sees fit. Smokin'.
If not smoking guns what are they? Near smoking guns? How many of those do you need to detect a pattern? Three legs makes for a pretty stable stool.
