For the scenes on the motorway, the production got permission to shoot on the M1 on a Sunday morning between 7.00am and 9.00am. The police gradually slowed traffic in both directions. Using 10 cameras, the filmmakers managed to capture a total of one minute of usable footage.
Athletes were cast as the Infected because of how important physicality is to them. Danny Boyle felt that since athletes can do things other people can't, they would be interesting when translated into the movements of the Infected.
The scene where Jim and Selena celebrate with Frank and Hannah was shot on September 11, 2001. Danny Boyle said it felt extremely strange to shoot a celebratory scene on that particular day.
The film was shot almost entirely in sequence; only pickups and a few reshoots were shot out of sequence.
The extras who played the dead bodies in the church were college students who volunteered to appear in the film.