When Pam and Jim get out of a car to enter the bar, it is obvious that outside it had been raining, because the ground is wet. However, beneath the car the ground is dry, suggesting that the car had been parked there for some time, rather than them just arriving.
Oscar says he has only spoken to Matt once at the Christmas party and once this morning. Just two episodes previous (St. Patrick's Day (2010)), Oscar and Matt are standing together at the bar for St. Patrick's Day.