The 7th Psychological Operations Group, which in this movie is based at the fictitious Fort MacCallum, Georgia, does exist. It is a psy-ops unit of the United States Army Reserve. It has its headquarters at Moffett Field, California. Until 1994 it had its headquarters at San Francisco's Presidio. The 7th has four battalions at four different Army posts. No listing for a 5th Instructional Detachment appears in any searchable record.
No Army post named Fort MacCallum, in or out of the State of Georgia, exists or existed. The nearest real-life counterpart might be Fort Benning, near Columbus, Georgia, and nearly straddling the Georgia-Alabama border. But no psychological warfare unit or school exists or existed at Fort Benning.
(Around 31 mins) when Brenner and Sunhill are in Capt. Campbell's office, you see colonel Moore in the reflection of the window pass by, then in the next shot he is standing at the door asking why they are in Capt. Campbells office.