The error was not picked up by the starters when checking the brands before the race while Lindsay Park co-trainer Tom Dabernig was fined $3000 for the mistake.

Racing Victoria deputy chief steward Rob Montgomery said Independent Road and Peidra ran in Saturday's race and later disqualified after each had finished near the tail of the field.

Regan Bayliss was to ride Independent Road but he ended up on Peidra.

Jye McNeil was booked for Peidra and partnered Independent Road.

Both horses finished unplaced in the race won by Riddle Me That.

The error wasn't picked up until after the running of the Golden Mile when Dabernig self-reported to stewards.

"Mr Dabernig came and reported it to us after race eight after one of his staff reported it to him," Montgomery said.

"It was an honest mistake but a costly one."

Montgomery said the starters, Corey Mallyon and Errol Gath, would be referred to RV's human resources department.

The controversy overshadowed Riddle Me That's impressive win in the race for the Matt Laurie stable.

The second favourite held off Score and the fast-finishing Zousonic for the biggest win of his career.

"He is a smart horse. He has come back really well this preparation,'' Laurie said.

"We didn't draw so well last start, he ran particularly well at Flemington. Obviously we had another wide draw today which I was a little bit disappointed about.

"It was a great ride from Daniel (Stackhouse) and it is good to see him get a good win.

"Daniel slotted him in perfectly behind the right horse. He is a tough horse and he has got that galloping style where he really gets his nose out and that was enough to get the job done today."

Laurie was unsure where he'd head next with the talented three-year-old.

"I think this horse can continue to improve, he has done that every preparation,'' he said.

"I would have to look through the calendar and talk to the owners about what we do next. Obviously, everything has been thrown into disarray. This was a target and it is good to get it done."