When Kirk, Spock, McCoy, and Decker go outside the ship to meet Vejur, they are wearing tan jackets. On the upper left sleeve each jacket has a colored stripe which denotes which division the officer serves in (white for Kirk and Decker, orange for Spock, and green for McCoy)

After Vejur evolves and the crew is back on the bridge, Spock and McCoy keep their jackets on with the colors listed above. However, when the camera zooms in on Kirk as he gives the order, "Out there.....thataway," take a quick look at the two of them standing behind Kirk's chair. Spock's jacket has a green stripe, and McCoy is now wearing the orange one.