Factual error: When Reacher is talking to Major Turner's lawyer Col Moorcraft he is wearing Military Police Corps insignias (Crossed Pistols) on his uniform, not the insignia of the Judge Advocates General (JAG) Corps (Half Wreath with arrow and sword) which is what an Army lawyer would be wearing on his or her uniform.
Factual error: On the plane Major Turner states she has been in the Army 10 years. She means after she graduated from West Point. Even accounting for super fast promotions, if she has been in for 10 years from age 18, she is too young to have had 3 promotions to Major and have the command she does in the movie. Even after 10 years out of the academy, this would be very quick.
Answer: Although it's technically a mistake, it is common in films to show military officers in dress uniforms with medals and ribbons to show that particular soldiers are important. A layperson may not know military uniform protocols but they can certainly tell that dress uniforms with a lot of medals signifies high rank at a glance.