Quarry tracks down his copy of Otis Blue and it is the Sundazed pressing released in 2012 complete with barcode on the back.
When Mac is flipping through the 100 dollar bills, they are modern day 100's.
There are "I 'heart' Tennessee" pennants for sale on the souvenir counter in the airport during the homecoming sequence. However, the "I 'heart' NY" campaign, which started the craze, didn't take place until 1977.
When Quarry, Arthur and Ruth are driving home from the airport, external landmark shots of Memphis are shown as they drive by them. At one point, they drive by Payne's Bar-B-Q, which is in Memphis, and the very next external shot, they drive by Twin Lakes Baptist Church. However, Payne's Bar-B-Q and Twin Lakes Baptist Church are about 18 miles apart, with the church actually being in Horn Lake, Mississippi.
While still in uniform at the airport after being discharged from the Marines, Mac has hair that is far too long as well as a mustache and long sideburns. The Marines don't allow hair to be that long or facial hair.