Running the anchor leg, Browning tripped and fell as Jack Hale held the baton out at the final change.
As Browning tumbled, Hale could only jog past resigned to the fact their race had been destroyed.
In commentary for Seven, Bruce McAvaney and Tamsyn Manou were both stunned.
“It’s all over – I cannot believe, I cannot believe it,” McAvaney said.
“A disaster, a disaster for the Australians.”
Browning told Seven after the race he was “gutted”, and apologised to his teammates and Australia.
“I’m so sorry. I know these boys put in so much work and in many years of athletics, nothing like that has ever happened and hopefully never again,” Browning said.
“I’m so sorry to these boys and everyone at home.
“Caught my toe and slipped. Like I said, never happened: never in training, never in races.”
As Browning unpacked the botched changeover, Hale put an arm around him.
“It’s a relay,” Hale said.
“There are so many variables. So many things happen. These things happen. It is what it is.”
For a daily dose of the best of the breaking news and exclusive content from Wide World of Sports, subscribe to our newsletter by clicking here!