Okla. Admin. Code § 325:60-1-17
When the horses have reached the starting gate, they shall be placed in their starting gate stalls in the order stipulated by the Starter. Except in cases of emergency as determined by the Stewards, every horse shall be started by the Starter from a starting gate approved by the Commission. The Starter shall see that the horses are placed in their proper positions without unnecessary delay. Causes for any delay in the start shall immediately be reported to the Stewards. If, when the Starter purposefully dispatches the field, the door at the front of the starting gate stall should not open properly due to a mechanical failure or malfunction of the starting gate, the Stewards may declare such to be a non-starter. Should a horse which is not previously scratched not be in the starting gate stall thereby causing horse to be left when the field is purposefully dispatched by the Starter, such horse shall be declared a non-starter by the Stewards. Should an incident or malfunction of the starting gate, or other unforeseen event compromise the fairness of the race or the safety of race participants, the stewards shall post the inquiry sign and may declare individual horses to be non-starters, exclude individual horses from all pari-mutuel pools or declare a "no contest" and refund all wagers except as otherwise provided in the rules involving multi-race wagers.
Okla. Admin. Code § 325:60-1-17