Excellent video angle of the rifle/uniform inspection (starts at about the 2:00 mark): http://www.youtube.com/watch?v=vqZ-mkdp1H0&feature=related
I was stationed at the Marine Barracks in DC from 1986 to 1989 and would visit my Army brethren at the Tomb from time to time to watch the changing of the guard. I remember one visit the Sergeant of the Guard spotted something amiss on the oncoming Sentinel’s uniform during the inspection and sent him back to the Crypt to correct it. He waited in position until the Sentinel returned almost 5 minutes later with the correction made. He resumed the inspection and then posted him. I often wonder exactly what was wrong on the Sentinel’s uniform.