Pressing F5 in Stress Test 54 (whether to lie down or surrender) results in items in hands disappearing from the world. And immediately causes player position issues. I.E. I am crouching but can move at sprint speed, standing but can't move at all, or surrendered walking but rubber banding back into place.
Frequently it will also cause me to not be able to utilize any items in my hand. I.E. holding an M4, but raising weapon just makes raises my fists with the gun floating behind me.