In a previous episode (season 1: Quinces) we are told Elena's birthday is October 7, 2001. In this episode, Elena is 5 weeks old on September 11, 2001 as the family watches a news report about the 9/11 attack.
In episode 1 series 1 Schneider says the family only moved in 10 months ago, yet in this episode it shows them moving in in 2001.