At the beginning, when they are leaving the Telegraph office after Quirt sends his telegram, the office door is alternately closed, open, closed when the telegraph operator is acting like he knows Quirt as he rides away in the wagon.
Doc Johnson: The practice of medicine is one of the most infuriating professions that have been known to man. It takes 30 years of practice to discover that, in the final analysis, there's nothing you can do but stand back and watch.