Rickochet but I don't know how many times a horse had a big lead then break stride coming down the stretch
Trotters. They do sometimes forget which foot goes next and where, or they do bang their feet in stride; something pacers cannot do. It happens in $1M races also, so not a 'fix', as some with losing tickets call it. Nature of the breed. Pacers will also sometimes, but typically it is the young ones, 2-3 yr. olds, for the majority. Older ones will also, but only something to be wary of when betting, when the program lines show it to be history. Not every race can be 'bet' on, but watched.π
And, Louisville was a 1/2 mile track. Something hard for certain trotters to negotiate sometimes.