Playing around, I noticed that using the quicksave can sometimes not reset everything back to it's original pre-quicksave state.
Examples;
Quicksaved before blowing up a bunch of cars. Blew up cars with grenades. reloaded quicksave.. cars exploded and grenades no longer in inventory.
Quicksaved before picking up some mines. .. mines blew up. Reloaded, mines were gone and the 2 that I picked up were still in my inventory.
Quicksaved before firing at bloatflies from a very long distance just to see if I could hit them. Emptied sniper rifle.. missed them all. Reloaded.. no bullets for my gun.