I'm curious about this too. A cursory search showed a couple of Politifact articles, one where Breitbart incorrectly said the Californian flag was supposed to be a pear, not a bear, and another where they mistakenly said that Loretta Lynch was a member of Bill Clinton's defense team.

My suspicion is that the people trying to muzzle Breitbart have never read it extensively. It has a very obvious conservative slant to it, but I've never seen flagrantly false articles by them (like the one claiming that Trump actually won the popular vote).