Factual error: Tiffany asks a guard where he would go if he could travel back in time. He says he would return to 1999 to attend a Judas Priest concert he missed. He says he wasn't able to get close to Rob Halford. The problem is Rob Halford was not the lead singer of Judas Priest in 1999. Tim 'Ripper' Owens was.
Character mistake: The officers count the inmates and say there's 10 missing. There are indeed 10 inmates hiding in the pool. However, Pennsatucky and Chang had escaped the prison. The officers counted Linda as an inmate, who had been hiding in Litchfield the whole season, and wasn't on the list. That would make it 11 people missing, not 10.