James Garner actually did serve with the 5th Regimental Combat Team in the Korean War.
During the film shot in Korea John wears a cap with long flaps to cover most of his head and face. This was necessary to cover his facial hair that would have been perfectly normal for a civilian in the 1970s but inappropriate for a serviceman during the Korean War.
When Jim follows Jennifer to work and exits his car building construction is visible behind him. Shown is the construction of the Pacific Design Center on Melrose Avenue. The Center Blue building shown here (also referred to as The Blue Whale) opened in 1975.
When Jim goes to John's studio, he finds John, standing atop a ladder, surrounded by 4 (visible) headshots. The one above Jim (and in front of John) is the actress Dorothy Provine. The shot right behind John (and unusually sized at 16x20) is Tammy Grimes (Ms Grimes is also seen in the shot behind John's feet). The picture of the dark-haired woman directly begging John is of the one and only Ms Julie London.