When Jack Reacher's car crashes into some barrels, the car accidentally stalled upon the impact, but Tom Cruise was luckily able to restart the car before driving off again. Rather than do a retake, Christopher McQuarrie decided to leave it in the film, as he felt it added to the suspense of the scene.
Lee Child, the film's source novelist, appears as a police desk sergeant who gives Jack Reacher his personal belongings back when he leaves jail.
Jai Courtney and Josh Helman had so much trouble with the American accent required for their roles that several planned scenes were scrapped, and many of Courtney's lines were dropped from the sides.
Reacher introduced himself as Aaron Ward, and it's obvious that Cash recognizes the name of the 1925 Yankees' second baseman. Cash pauses and says the name to confirm. Cash says, "Play ball!" after Reacher is allowed his practice shot, so now the real shooting can take place. That reference to baseball is a tip-off to Reacher that his cover has been blown, even before he takes his excellent shots to reveal who he is.