In the opening scene young Shawn lifts the blanket over his chest. When it cuts to a close up the blanket is lower on his body and he lifts it up to his chest the same way again.
Major General Felts is wearing a special forces combat patch but missing the airborne tab that goes with it.
Numerous times characters call the Army installation a base. The Army calls them Posts while the Airforce has bases.
When Gus and Shawn are at the beach, Gus refuses to set foot on the pier because according to him it is "soaked in pelican urine". Birds, however, do not urinate (including pelicans). They excrete a white paste (bird "poop") called uric acid from their cloaca.
Soldiers are not dropped for push ups as a punishment when they are no longer in training.
When a soldier is killed in combat, his/her dog tags are placed in the mouth or wedged between the teeth for identification purposes. Swallowing dog tags would actually BE the means of suicide as the soldier would choke to death on them.
Most of the soldiers are not wearing the covers (hats) when they are outside.
When Shawn & Ewan (John Cena) are talking privately near the end, Ewan incorrectly refers to Major General Felts as *Felps* more than once.
When Gus is doing push ups, he answers "No Sir" to some of the questions posed to him by the E-7. No self respecting Sergeant would ever want to be called or even allowed to be called Sir.