Source Code ending explained: What's Colter's eventual fate?

Source Code is a film in the science fiction action genre that was released on April 1, 2011, after its SXSW premiere a month prior. Duncan Jones is the director, while Ben Ripley wrote the script. The producers include Jordan Wynn, Mark Gordon, and Philippe Rousselet. Here's the official synopsis:

"When decorated soldier Captain Colter Stevens wakes up in the body of an unknown man, he discovers he’s part of a mission to find the bomber of a Chicago commuter train."

The film stars Jake Gyllenhaal, Michelle Monaghan, and Vera Farmiga, among others. Let us explore its ending and Colter's fate.

What is the plot of Source Code?

A still from Source Code | Image via Universal Pictures

Source Code chronicles Captain Colter Stevens, who is a pilot in the United States Army. He is commuting on a Metra train to go to Chicago. Stevens wakes up on the train and finds out that he is in the body of a guy named Sean Fentress. Just when he is trying to figure everything out, an explosion takes place on the train, which kills everyone on board. Later, he realizes he is alive and is sent back to the train to find its bomber in just eight minutes.

At one point, Colter is informed by Christina that he passed away in a helicopter accident a couple of months ago. He is clinically dead, and just a fraction of his brain is working. Through the Beleaguered Castle operation, his body and the capsule assist him in going on the missions called "source code," where he goes inside someone else's body to do something. In this case, he has to save passengers from a train explosion.

How does Source Code end?

Towards the end of Source Code, Colter Stevens finds out that the bomber was someone named Derek Frost, who was a terrorist. Colter goes into the code for the last time, ties Frost inside the train with handcuffs, and calls the cops to ensure the explosion doesn't happen.

But Colter wants to meet Christina Warren before he is fully terminated for the final time. Captain Colleen Goodwin then proceeds to terminate him and ends his life support so that he cannot be further used for such missions. She is arrested for defying her senior's orders.

Meanwhile, Colter's subconscious exists in an alternate timeline with Christina away from the main events. He manages to live beyond the eight-minute limit as the two spend time together. Towards the end, Goodwin is informed about more explosion prevention in the future. This cements that she is aware of the technology used to create the source code.

While it was started by Dr. Rutledge, he is not aware of it because Goodwin kept the information away from him. Colter, on the other hand, is living a peaceful life with Christina while being in another man's body.

Fan theories on Source Code

Reddit users have tried to decipher how Colter managed to send Goodwill a text from another dimension. One user has said that when he went inside Sean's body, he went inside an alternate parallel universe. It also has a copy of everything that exists in the real universe. Goodwin gets a text from Colter in the parallel universe, which she didn't get in the real world. In the parallel universe, Colter from the real world goes on to live his life as Sean.

Another user believes that Colter's brain was coming up with these situations after the eight minutes were over. He does not survive the explosion, and his mind is conjuring these situations for him. The ending manages to evoke different kinds of emotions and lets the viewers come up with their own theories.