Xibalba

The 2 cave divers you see diving in the real cave were diving with 2 side mount cylinders as well as a smaller cylinder (deco or bailout bottle) and were wearing normal scuba masks, one with helmet with 2 lights on the side (typical cave gear). Yet when you see ALL the divers come up, they are wearing full face masks, only have a single centre back mount tank. They also talk about being low on O2 (not air) and earlier discussed oxygen percentages they had left. It should have been how many PSI or Bar they had left. I'm sure they just took some stock footage of cave divers and put the rest in, but even non divers can tell the difference in gear.