The first goal can be blamed on 3 of the midfielders.
Firstly, we can't discount that cross from Messi to the opposite wing that completely broke Juve's defense. The defense was overloaded to the right side and with a single pass Messi switched play to the open side and started a chain of events that had Juve scrambling to recuperate positions without avail.
Then for the goal, 3 things happened:
Firstly, Vidal fell asleep and totally lost Iniesta and allowed him to make an unmarked run into the box.
Secondly, Pirlo, who was in the area Iniesta received the ball, seconds before left that area to go mark a run initiated by Messi. He was the one who left the are open for Iniesta.
Finally, yes, Pogba lost Rakitic and allowed him to shoot unmarked in the center of the box.
I think of the 3, Pogba's mistake was the least harmful. IMO Vidal losing Iniesta was the most egregious mistake, followed by Pirlo leaving the are to go mark Messi.
But really there were no unforced mistakes here. Everything that happened was caused by Barca making a great play and leaving Juve with little reaction time to stop them. The entire team there played a role in that goal one way or another. Look at Suarez hold 2 players inside the box for instance.