The 22-year-old disabled skier had a 2sec buffer after he blitzed his opening run.
But a tumble two-thirds down his final run threatened to end his dream.
Hall, who has spina bifida, scrambled to his feet and pushed off determined the mistake would not cost him the gold medal.
"I think every New Zealander on the hill at the time had a collective heart attack," chef de mission Jon Turnbull said.
"But he is gritty bugger and that is what has got him to where he is - that quiet determination.
"He got right back up and didn't miss a step.
"I think he actually made up some lost time flying through the last five gates."
Back in New Zealand, winter performance programme director Ashley Light was watching on television.
"There were some sweaty palms and dry mouths when he fell over," he said.
"But the great thing is he recovered so quickly and, obviously, his first run was so exceptional that he had that buffer.
"He did very well given his disability to get up as quickly as he did and ski off."
To understand how Hall, a snowboarder at heart, was able to get himself off his backside and back into the race so quickly you have to turn the clock back eight years, Light suggested.
"He watched Steve Bayley and Rachel Battersby win gold at Salt Lake City and came and said `I want to win gold', but was actually a snowboarder at that point.
It was pointed out to him snowboarding might be pretty cool but you're not going to win a Paralympic event."
Hall made the switch and has not looked back.
He went to the Turin Games in 2006 and learned what it would take to win a medal.
He vowed to win a medal at Vancouver and yesterday realised that goal.
"The whole of New Zealand can feel very proud of him," Light said.
"He has achieved his goals and I'm sure it means everything to him."
Light has been working with Hall since 2002 and said he had come a long way in that time.
"He has developed into not only an exceptional athlete, but an exceptional young man and a real ambassador for New Zealand as well."
"He is one of those hard Otago-farmer types.
"In the early days when he didn't have the support and the investment he is getting now, he had ways of surviving which involved a whole lot of duct tape."
Duct tape? "He strapped his knee up with it when he had a bit of a bang.
"Part of his spina bifida means the muscles around the joints of his lower legs aren't as strong as able-bodied legs.
"He has had a bit of an issue over the last 18 months with dislocating knees.
"We haven't wanted to go under the knife with him because of the Games.
"He is as hard as nails."
Hall's combined time of 1min 45.40sec was 0.57sec better than German Gerd Schonfelder with Australian Cameron Rahles-Rahbula third.
His gold medal was New Zealand's first medal at the Winter Paralympics since Rachel Battersby won three golds, and Steve Bayley a gold and two bronze, eight years ago.
He still has the giant slalom tomorrow, the super G on Sunday and the super combined on Monday.
Turnbull believes Hall has a chance of a podium finish in the super combined.
"He is so strong in the slalom and if he can get a good super G run he is an outside chance.
"Certainly top five, top 10 is not out of the question."
