This episode shows one of the main blast doors to Cheyenne Mountain Complex closing. The second one, including much of it's locking mechanisms is seen behind it, still stationary. Together, in real life, they are rated to protect the complex from a Nuclear Explosion of roughly 30 megatons as close as 1.2 miles away and are typically closed only roughly once every 6 months as a test to assure their ongoing ability to close. They weigh roughly 25 tons each.
Kevin Conway plays an unnamed leader of SG-3, revealing that for some reason, Colonel Makepeace is temporarily reassigned or off duty.