Depleted uranium will not trigger a Geiger counter reading like plutonium.
The bar fight in the opening scene included several enlisted Marines, all of whom are wearing Army stripes (gold on a green background, instead of USMC green on khaki) on their short sleeve shirts. There's also a Marine with a full beard; never allowed, except for medical necessity.
Before the explosion of the booby trapped Jeep develops Will and Frankie jump like already been hit by the shock wave.
Will mentions Jimmy "rising through the ranks" of the Marine Corps, and that he was retiring. It was later revealed they had served together 16 years earlier. Both Jimmy and Will were wearing Captain's bars on their uniforms. A Captain in the Marine Corps is an O-3 rank, one that would take about 4 years and 2 promotions to attain. A Marine officer retiring after the minimum 20 years would usually have attained a far higher rank, such as Lt. Colonel (O-5) or full Colonel (O-6).