For the future scene at the end of the film we are told it takes place at "Aitken Basin - South Pole" and that it's at 16 48 S. Latitude. 16 48 south latitude is nowhere near the south pole. It's much closer to the lunar equator that to the lunar south pole.
In the surface emergency sequence, when one astronaut's portable life support system fails, he activates his OPS (Oxygen Purge System), i.e., emergency oxygen supply. But he fails to open the purge valve that lets the oxygen flow through and out of his suit. The valve is unlocked by pulling a pin attached to the red ball ("red apple") hanging from the lower right front of the suit.
In the surface emergency sequence, neither astronaut has anything connected to the headset/biomedical connector on the front of the suit below the left shoulder. This may explain why they had trouble communicating.
In the emergency scenario the spacesuit connectors for cooling water and oxygen from the PLSS (Portable Life Support System) are reversed and the BSLSS (Buddy
Secondary Life Support System) hose is incorrectly connected between the suit oxygen inlets. The BSLSS shared only the cooling water from a single working PLSS, not oxygen. This allowed the astronaut with the failed PLSS to extend his emergency oxygen supply.