Jake Gyllenhaal had an ear bud on during the train sequences, into which the director would start playing music at any point of time, which helped Gyllenhaal's character to look disoriented . The director played random songs as well as "static buzz" at times.
Russell Peters did about an hour of stand-up with his own material for his scene. Because majority of his jokes were full of adult themes and graphic language, most of them were cut because of the PG-13 rating.
Because the owners of the actual commuter station they planned to film in changed their terms at the last minute, a fake station had to be built in a car park. That meant the white van couldn't be prepared in time. The contents had to be simulated using CGI.
Vera Farmiga stated that she took the role just at the start of her pregnancy in February 2010. She knew that in that scenario she would be unavailable for the next 10 months. She filmed her scenes in 10 days.
The commuter train map posted inside the rail car, was actually the map of the Chicago Transit Authority (CTA) with the color of the lines altered. The train being filmed was also a Metra train, an entirely different rail system, which features no maps at all in its cars.
Lindsay Lohan was originally cast in the role of Christina, however, producers decided to recast the role when her legal issues conflicted with the filming schedule. Michelle Monaghan was eventually selected as her replacement.
Colter Stevens (Jake Gyllenhaal ) tells Christina Warren (Michelle Monaghan ) that his brother went missing in battle in Afghanistan. This is later resolved during the film but also mirrors the beginning to Brothers (2009), another Gyllenhaal lead film.
During Max's stand-up routine, his punchline includes the names "Barack" and "Michelle". Barack Obama (44th US President) and his wife Michelle Obama are officially residents of Chicago, Illinois where the film is set.
The pilot episode of Quantum Leap features the main character played by Scott Bakula jumping into someone else's body in the past, and the episode ends with him calling and talking to his father, as he is still alive during this time. in the final scene of source code, when the main character similarly takes advantage of being in the past to call his deceased father, the father is voiced by Scot Bakula.
This film contains several references to the two movie versions (1962 and 2004) of Richard Condon's book The Manchurian Candidate. In both The Manchurian Candidate and Source Code, a main character is a decorated U.S. military veteran who has returned stateside but who is (without his knowledge) still being used as a tool in a secret military program. In both the book and first movie version of The Manchurian Candidate (1962) and in Source Code, the man is "triggered" by a code involving playing cards, and in both cases, a queen is the card used prominently. Two of Source Code's main actors (Vera Farmiga and Jeffrey Wright) also had prominent roles in the 2004 film version of The Manchurian Candidate (2004).