It is not that hard to crash when warming up.
You have
Young colts and fillies
Water trucks
Tractors pulling loud drags
Horses turning before their mile and again after
Horses going in both directions and all speeds
Horses coming on and going off the track
Hot dog wrapers blowing across the track
Loud noises and shouts from the grandstand.
Was there ever a lot of crashes the night at Sporsman's Park, when Tina Turner was singing "Rollin On The River" while we were warming up.