As a retired military man the instant I see a film with a "Soldier" wearing a goatee or beard, massive uniform deficiencies, improper slang, ridiculous protocols, improper weapons handling, incorrect IMT or half assed crap discipline I grit my teeth. Please at least Google the jargon before you shoot.

"28 Days Later" got it right with the British army unit. The BA is the most professional and well disciplined army in the world. Once they started screwing around with the car and altering their uniforms I knew discipline was gone.
It does not hurt to ask for military support from your state national guard or the DOD film office. All they can do is say no.
Please use real soldiers or recent veterans of appropriate skill/rank in your projects.
Volunteers are easy to find and they will be more than happy to help for a free lunch.

Here are some free tips;
  1. In the US military women do not serve in the infantry, armor(tanks), or special forces/Seals. Nor do they go on SOF missions. They are medics, pilots, mechanics, MPs, Intelligence, etc.....
  2. Generals/Full Colonels never ever ever go on missions ever they get in the way.
  3. Vehicles. If you cannot get access to authentic vehicles please don't use civilian versions. Too easy to spot and they are as distracting as a floppy beret.
  4. Civilians do not command. They advise, assist or provide support.
  5. US military units from squads to divisions deploy in Task Forces. ie, "Task Force Bayonet" never as a single infantry company.
  6. US military always names its operations. ie "Desert Storm", "Linebacker", "Enduring Freedom".