Dragon Plays with Fire - S1-E13
Trivia: When Claire talks with Jeri on the street, there is a poster on a wall with Stan Lee on it.
Rolling Thunder Cannon Punch - S1-E3
Trivia: The white jacket worn by Colleen resembles her outfit in the "heroes for hire" comic series.
Trivia: The news on the cell phone seen by Danny is written by Keira Morrisette - she is a co producer of the show.
The Mistress of All Agonies - S1-E9
Trivia: Joe's Pizza is the same place shown in Spider-Man 2.
Shadow Hawk Takes Flight - S1-E2
Trivia: Danny has his passport in the name of John Anderson. In the comics that's a neighbor of Peter Parker.
Eight Diagram Dragon Palm - S1-E4
Trivia: The stickers on Danny's desk are Orrgo, made by Jack Kirby, and Mangog, made by Kirby and Stan Lee, shown in Strange tales comic series.
Answer: Sokovia is a nation in the Iron Curtain. It is just as likely for a US operative to end up there as any of the other former Soviet nations. There is no reason to believe she was there at the same time as the Avengers. It was likely some form of covert mission there years beforehand.