Josh Lucas plays the father in the 1958 case, a character named Matthew, and his three sons are named Mark, Luke, and John. Taken together, those are the names, in traditional Catholic order, of the New Testament's four canonical gospels of Matthew, Mark, Luke, and John.
Screenwriter Glenn Taranto wrote his first draft of the screenplay, originally titled "The Boy in the Box", in six days over a two week period. He was inspired by the famous unsolved case of "America's Unknown Child" aka The Boy In The Box. Working backwards Glenn created an original scenario detailing how such an unsolved crime might have occurred. Should anyone have any information regarding the real "Boy In The Box" case they are encouraged to contact the Philadelphia, PA Police Department.
At the time of filming in 2008, Rhona Mitra, who played Barbara, was 32 years old. Barbara says that eight years after his disappearance Tommy junior would now be 18 years old. Since Barbara appears to be the same age as the actress, that would mean that Barbara would have been about 13-15 years old at the time of Tommy junior's birth.
In the 1958 part of the story, Matthew refers to the car he drives as "the Rambler." In fact, the car is a 1958 model, which was a new body style, and the first Rambler model designed and built by American Motors Corporation as the Rambler Ambassador. All previous models to 1958 where Nash Ramblers (1950-1957) or Hudson Ramblers (1954-1957), which were the constituent companies merged in 1954 to form American Motors Corporation.