When the alien's gas regulator begins to malfunction when he first confronts Lawrence and Elliott, he tries to turn the knob on his suit while standing up. But the close-up of him trying to turn the knob is an insert shot of a scene late in the film, when he is lying on the ground and again attempting to turn the knob back on.
Enid's car had a blow out on the night it failed. When John Lawrence went back. He simple took a small air pump and pumped the tire up. And went on about his way. When a tire blows out it destroys the tire. At the very least it would require patching before it could hold air. And in most cases the blowout is the result of a catastrophic failure of the tire. And once the tire fails. Even more damage is done to the tire before the car can be brought to a stop. The damage gets worse because you drive on the flattened tire. And the rim damages the tire.