At the time of the film's release, the Army had already replaced its green camouflage Battle Dress Uniform with the pixel-gray Army Combat Uniform. Even if for some reason their unit hadn't gotten ACUs, the BDU is still worn improperly by every soldier in the film. They should have unit patches on the left shoulder, and an American flag on the right shoulder.
CPL Cross ends a radio transmission with CPT Rhodes with "Over and out." "Over and out" is a contradiction. "Over" means "I am finished speaking, please reply." "Out" means "I am finished speaking, do not reply."
Captain Rhodes wears matching Captain's bars on the lapels of his uniform. Army officers only wear rank insignia on their right lapel. The left lapel is reserved for that officer's branch insignia, i.e. crossed rifles for Infantry, crossed sabers for Cavalry, crossed pistols for Military Police, etc.
In the radio station right after Paul (Disc Jockey) turns into a Zombie and gets killed, Nina kneels down near a desk next to a computer. The computer is empty, it doesn't have any electronic components in the back like a video or network card. It's clearly a prop.
When Cpl Cross first arrives at the hospital with her mother there is a little boy being pushed in a wheelchair at the bottom left of the screen; despite being ill the actor is clearly smiling and looking straight at the camera.