How to Throw Cargo
You can pick up any piece of cargo with your hands by pressing R2 and L2 (which correspond to your right and left arms, respectively). While holding those triggers, if you press Square, you’ll swing the case around. This can deal major damage to any enemy in range. If you let go of the trigger after pressing Square, however, Sam will toss that particular piece of cargo altogether.
This comes in handy if you’re trying to attack MULEs from afar. You can also use it to chuck an item that’s fallen off your back out of the black goo, toward safety, when you’re caught by BTs.