Just something I recognized a few minutes ago.. 

1. ) When you watch the (extended) Promo for S06x06 (The Red John Episode) - many have mentioned that the guy jumping through the glass looks a lot like McAllister. Could be. 

2.) Just re-watched the scene ( S06x03) where Patrick calls McAllister while being in the forest. 

-McAllister sounds ALOT like Red John on the phone ( listen to his voice saying "Sheriff McAllister... What can I do for you Patrick?") and compare that for example to the last phone call of Red John in the first Episode of Season 6 (at the End). 

AND: 

When it comes to the Promotion of the Red John Episode - the voice (which is Red John i presume) says "The game is over and I won!" - and McAllister (in the conversation mentioned above) says something like "Game is game, isn't it?" when they talk about hunting. 

Another clue? I don't know. Just thought it could be interesting for you guys as well :)