The LaTeX renderer interacts badly with markdown differences. Since markdown differences are raw source-code, the LaTeX renderer should ignore it.
For example http://crypto.stackexchange.com/review/suggested-edits/1633 renders broken markdown on the right.
Screenshot (Opera 12.02):
It only happens when I'm logged into crypto.SE, which explains why it only occurred in Opera and not FF for me. Clearing cookies fixed it, until I logged in again.