Jockey Martin Pedroza was unseated from 3-2 favorite All Net a few strides after the start of Saturday's ninth race when the 3-year-old filly stumbled severely.
Pedroza was on his feet after a few moments. Track officials said Pedroza was not injured.
All Net, who was claimed for $6,250 in a seven-way shake by Rosemary Trela, ran behind the other runners through the five-furlong race, which was won by My Ebony Star ($46.80).