Directed by: Duncan Jones
Starring: Jake Gyllenhaal, Vera Farmiga, Jeffrey Wright, Michelle Monaghan
Other mistake: When the conductor / ticket inspector is checking tickets, why doesn't he check Christina's?
Suggested correction: Perhaps she boarded the train before Sean at a different stop, and the conductor had already checked her ticket.
Audio problem: This scene is repeated multiple times in the movie: usually when the main character enters the "source code" the scene begins by panning over a small pond showing a Canada goose taking flight. However the sound editor makes the mistake of dubbing in a recording of a hen mallard duck.
Colter Stevens: What would you do if you knew you only had one minute to live?
Christina Warren: I'd make those seconds count.
Colter Stevens: I'd kiss you again.
Christina Warren: Again?
Trivia: The voice of Jake Gyllenhaal's father is Scott Bakula, who starred in Quantum Leap, which shares the premise of being in another person's body with this movie.
Question: What happened to the real Sean Fentress?
Answer: He died in the train bombing along with all the other passengers. If you're asking what happened to the real Sean Fentress in the alternate time line created at the end of the movie, Colter took over his body and continued to live the life that Fentress had been living.