Michael Dore, head of totalisator betting at TAB, said there had only been three incidents in the last five years where betting had accidentally remained open due to human error.
"Generally, it's been 15 to 20 seconds into the race that a person has been distracted or held up on the phone where they've missed the start, which isn't quite so fatal because the race hasn't concluded," said Dore. "But this one, as you can imagine, two minutes after the horses had crossed the finishing line is as bad as it gets."
Dore added that all the precautions and alerts warning the worker the race was about to start were missed.
"The operator knew they made a mistake and they fessed up straight away which is the right thing to do, it's not something you can sweep under the carpet," said Dore.
The TAB will meet with the worker tomorrow to investigate what happened.
Dore said that the priority yesterday was to refund all the money placed on the race back to customers, including those who had bet on the winning combinations.
"It looks pretty ugly and obviously being very late at night we had the security of knowing virtually all of the bets placed on the race were placed via account bets, which means we can just deposit it straight back to them."