After Ciki shoots Nino and the old soldier, he loads the other of the together taped magazines in the rifle and makes a loading movement, thus cycling the first round in the chamber. A bit later, in the "who started the war scene" in the bunker, Ciki shouts "who started the war?" and makes another loading movement, which would cause the first round to be ejected (unspent) from the rifle. Yet no round is ejected.
When Nino and the Old Veteran plant this mine under Cera, the mine is an M16 Bounding mine. This mine is designed to explode after weight is applied or the pin is removed. They add weight and remove the pin which is redundant.