Factual error: Filming location is Budapest instead of Moscow, you see HU license plates on cars, HU street name tags, and even the flag of HU and the EU waving over the building Carrie is on.
Why Is This Night Different? - S5-E4
Factual error: The airport is shown as Douvaine in Switzerland. Douvaine is actually in France.
Chosen answer: Everyone else calls him Brody or Sgt. Brody, and it probably became habit to her.
The_Iceman
Can't get the source but I read that even the Producer responded to that. Stating that it was common practise for a military wife living in a military complex as everybody refers to their husband by their last name.