Neeson revealed on a talk show that no scenes were filmed on board an actual train. Instead, all of these scenes were shot on a soundstage, with the same single mock-up train cabinet serving as all of them, only slightly redressed, and all the outside scenery added in post production with the help of green screens.
Despite receiving the prominent second billing, Vera Farmiga has only about 6 minutes of screen time.
The sixteen personalities that Joanna refers to when she strikes up the initial conversation on the train are the Myers Briggs types.
Towards the beginning of the film when Neeson's character is walking through Grand Central Terminal, there is a poster for Paddington 2, which shared its US release date with The Commuter on January 12th.
The second film to feature Vera Farmiga and an incident on a commuter train, following Source Code (2011).