To prepare for her role in the series, Claire Danes met with CIA officers, and also watched videos made by bi-polar disorder patients and consulted with author Julie Fast who suffers from the same disorder.
In a December 2012 New York Times interview, Howard Gordon explained why Jessica calls her husband "Brody," his last name, instead of his first name, "Nicholas," or any nickname form thereof: "It's something that's been in their relationship from the very beginning and speaks to the love between them. We've heard from many military families, and it's not that uncommon a practice."
British actor Damian Lewis landed the lead role without an audition. The series producers Howard Gordon and Alex Gansa were so impressed with his performance in the under-rated Keane (2004), they offered him the part over the course of a phone call.
Although Carrie's condition was not specified during the show's first few episodes, the actor who plays her, Claire Danes (who considered majoring in psychology at Yale) told "Entertainment Weekly" that she decided that Carrie has Bipolar 1.
Claire Danes stated in an interview that writer Meredith Stiehm was deeply involved in writing the character of Carrie, not only because Stiehm was the only female writer on the show but also because her sister suffers from Bipolar disease.
The American series is based on an Israeli drama series called 'Hatufim' (Hebrew for 'Abducted' or 'Kidnapped'). Gideon Raff created the original series in response to the many Israeli soldiers who had been enemy captives and their brutally difficult, and largely unreported, efforts to reintegrate into Israeli society after they returned home. One of the major differences between the Israeli and American series is that whilst in Homeland, Brody was apparently rescued, in Hatufim the POWs were traded.
The trivia item below may give away important plot points.
Brody was going to die on season 1 with the bomb-vest device, but Showtime encouraged Alex Gansa and Howard Gordon to keep the character alive as much as they could, which ended up being three seasons.