Filming was halted for six weeks after Richard Gere dislocated his shoulder during a fight sequence with Tamer Hassan.
In the police station, shortly after Agt Geary becomes suspicious of Shepherd, one of the pictures on the Cassius investigation wall behind Geary and Oliver is the controversial JFK "Front and Back"autopsy sketch drawn by Rear Admiral George Burkley. Interestingly, it is the "original" sketch signed by Dr Burkley on the bottom left of the page. The same sketch that appears in the Warren Commission Report bears no signature.
When the names of the two male leads are shown in the opening credits, there is a "backwards R" used once in each of their names. This letter is from the Cyrillic alphabet, and most westerners recognize it as connected to the Russian language. The last letter in that alphabet, It is pronounced "ya" and by itself, means "I" or "me." Thus, it hints at an answer to a pivotal plot point: Cassius's real identity.
A recognizable name for her role as Kate Beckett on Castle (2009), on which she was also starring at the time, Stana Katic receives fifth billing in the opening credits, but only has about five minutes of screen time.
Randy Flagler and Yuri Sardarov both starred in Chicago Fire together.