After Fred Derry dresses after staying the night at the Stephensons' home, he emerges in his uniform with his jacket belt-buckle positioned way off to the right, over his right front pant's pocket. Any real serviceman would position his belt buckle (pants or jacket) dead-center, directly over his pant's zipper flap.
During Al Stephenson's speech at the bank get-together party, he talks about his division being in Okinawa. The 25th Infantry Division (Tropic Lightning), was part of the Luzon campaign that started January 1945 and ended with the divisions relief at the end of June 1945. At no time was the 25th on Okinawa. The divisions that did participate in the Okinawan campaign (April 1 - June 22, 1945) were the: 7th, 96th, 27th, and 77th Infantry Divisions of the army and the 1st, 2nd, and 6th Marine Divisions.
When Fred Derry climbs into the B-17's nose compartment at the salvage field, the nose section noticeably wobbles as he steps into it, indicating the nose is a separate, detached set piece. The nose section on a complete, intact B-17 would not move like that.