Everyone acts like the 5.56 round is something new. The M16 rifle (which uses that particular round) had been introduced ten years before then and it would have been known by every soldier.
Although it is not mentioned explicitly, there are a number of references, especially to the town of Seaside, suggesting that the base where Col. Bowie (Frank Maxwell) was stationed was Fort Ord, which was located near the Monterey County town of Seaside in central California when this episode was made. At one point Rockford also tells Billy Webster (Charles Napier) that he's "in town for Colonel Bowie's funeral." The scene at the end that is supposed to be at that funeral, however, was actually filmed at the Wayfarers Chapel, which is located several hundred miles to the south in Rancho Palos Verdes near Los Angeles - there is even a plaque identifying the church as the Wayfarers Chapel visible behind Rockford and Shana (Jesse Welles) as they stroll nearby.
Col. Hopkins hands Jim an M1911A1 pistol and tells him "The safety's on the right", giving him a subtle dig at his reluctance to use weapons. The safety on the government-issue M1911A1 is on the left, under a right-handed shooter's thumb (making it easier for the shooter to flick the safety).
When Shana takes Rockford into her father's house she shows him her father's "campaign ribbons" displayed in a frame on the wall. But since her father was still on active duty, he wouldn't display them in a frame, he'd be wearing them. (Note: Shana could've had the ribbons framed after her father's death).