Five jockeys have been suspended for 12 days for taking a wrong turn.
The incident happened at Newcastle during the two-mile, six-furlong Gosforth Decorating And Building Services Mares' Maiden Hurdle.
"They had their heads down and didn't realize where they were going," course stipendiary steward Adie Smith told the BBC. "When they realized they'd gone the wrong side of the hurdle track, they tried to pull back, but the momentum had taken them past the point of no return."
Jockey Jason Maguire, atop Seedless, led the mishap followed by four other horses: Catleen (ridden by Peter Buchanan), Glen Innis Lady (James O'Farrell), Moscow Mischief (Campbell Gillies) and Ruby Queen (Paddy Aspell).
"I knew the rail was there, but with a lot of runners it couldn't be seen by those behind until too late," said Gillies. "It was marked on the board in the weighing room. You would have thought someone would have spoken to the jockeys beforehand to make sure we were aware of it."