Toward the end Jody grabs Pappy's suspenders from the back and the bottom disconnects from his pants. After Pappy breaks free and moves toward the house the suspenders are reattached to his waist.
Captain Salbo tells one of his men, "Get me SAC Headquarters in the Pentagon"
SAC has been headquartered at Offutt Air Force Base in Nebraska since 1948, well before the time frame of this story.
Early in the film the Captain Salbo character wears a tropical Army Class A uniform, without decorations; decorations are mandatory on this uniform, especially with his service record described in the dialogue. Elvis' lieutenant character also wears Air Force service dress (Combo 1) with pilot wings but no decorations. USAF officers in 1964 would have at least the National Defense Service Medal. Also, military creases are not allowed in USAF uniform shirts, as Elvis' character wore.
Cpt. Salbo says the government wants to lease the Tatum's land. They would never just lease it; they would buy it outright, and if they refused to sell, they would have claimed it under the power of eminent domain.
Captain Salbo introduces himself as being from SAC, the Air Force's Strategic Air Command, but he is wearing an Army, not an Air Force, uniform (as are all the enlisted men).