If u r referring to DP's try, he didnt scored that goal actually...
The penalty wasnt a penalty as their defender touched the ball before DP,
but it was really hard for the ref to see that and DP has been abused by Catania defenders during the whole game.
The ref tried not to show any red cards and intimidated with yellow cards all the fierce taclins off target. I dont think he had ill intentions.
The yellow card on Chiellini was his worst call, that should be the other way.
As about their goal being offside, i think not, it wasnt offside, Molinaro kept their forward on game being in the same distance to the goal as him,
this year linesmen in Italy were ordered to give the advantage at attackers, at similar cases
(inzaghi must be jubilant)