Tonia implores Obreon to stop the killing, as he has already killed three men. He then kills another, making the tally four with only Salvador remaining. In a later scene, Captain Rodriguez tells the soldiers that Obreon has killed three men (not four).
The same snow/ mountain backgrounds are used in several different scenes to represent different places.
The refuge at the Shrine would not have such big windows as there would be considerable heat loss through them. There would also be shutters on the windows to protect them during storms.
Obreon and Salvador are supposed to be following a route across the mountains. However, they end up walking up an extremely steep slope which would not be part of any mountain route.
Rodriguez would not shoot at the Shrine's refuge to get Obreon's attention. He runs the risk of killing/ injuring someone inside. He (or his companion) would shoot into the air to get Obreon's attention.