Dr. Flug is looking for Black Hat and is about to ask 5.0.5. where he is until he notices that the manor has been decorated with Christmas decorations. Dr. Flug sees Black Hat decorating a Christmas tree and asks if he is trying to throw a party, stating that he did not know he celebrated Christmas. Black Hat states that he is not celebrating Christmas, but the end of the world.
Black Hat celebrating the end of the world is likely a reference to how some perceived the Mayan calendar ending at 2012 signified the end of the world.
This is evidence to suggest this episode takes place in December of 2012.