During the opening of the episode, the TV shows the Berlin Wall coming down. However, this contradicts season 2 episode 17 "The Adam Bomb", in which the plot is resolved with Barry seeing the Berlin Wall fall. Adam looks, sounds and is older in this episode, meaning these two episodes cannot happen at the same time.
At the beginning, the narrator says that it's November 7. However, the fall of the Berlin Wall is shown on TV, which took place on November 9.
It's established in episode 4.21 ("Fonzie Scheme") that Murray has no hobbies. This contradicts the fact that he's been collecting stamps since childhood.