Watch the scene where the comancheros are robbing the wagon with the grandma, her daughter and killed the man. After the robbers pull Sondra Locke out of the wagon they then proceed to rip her clothes off. Slow the footage down to frame by frame and if you are quick enough you can see Clint Eastwood wearing a white shirt sitting in a "directors chair", along with other people. There is only one frame that shows this.