In the beginning John Cena is talking to a Marine officer outside. The officer's uniform is correct, but Cena is wearing a U.S. Army style camouflage cap with no insignia. Anyone familiar with the Marine Corps knows that they have a unique pleated cap with the globe and anchor symbol on it.
Marine utility covers are called "8 point covers" because they have 8 points on the top. And they are not worn like baseball caps like he wears it in this scene. And furthermore, he was not wearing the utility blouse, so he should not be wearing a cover at all. You don't wear a cover with boots and utes. Any Marine knows that.