I joked about it earlier, but in all seriousness..
How in the fuck did this happen 
I've been to every rinky dink county fair in Ohio..over 40 years running
I have seen some messed up stuff 
I have never seen this happen 
Has anyone else? Honest question
Not a harness racing incident but fits the mold of what happened. Recently, a quarter horse race down south at a track running a quarter horse meet. Last race of the day, new ambulance driver. Guy is waiting by the chute where the races generally start. Realizes way too late the last race is around the hook. Decides to beat cheeks to try to get to the starting gate in time. Because he is not clued in at all, decided to drive along the inside rail...the wrong way. So instead of making his way to the gate by driving counterclockwise, he decided to save time. Wasn't enough though, he is still rounding the far turn when the field comes right at him. Oh and the announcer was really in no place to do much since the ambulance was well concealed by the rail.
The horses on the front end saw the danger with plenty of time and went way wide. The next horse in line along the rail therefore had some lead time and the jockey basically yanked his head off for the rarely used full gallop right turn. The last jockey on the rail probably shit himself, but had just enough time to avoid the head on collision.
So disaster was avoided...barely. And for those wondering...racin
g horses don't seem to react to impending head on collision doom in the way you might expect. There are been more than a few head on collisions horse vs horse. and in nearly every case both horses die.
As for Howard Oil, I grew up going to the races at Monti and loved his race-calling. However, that was nearly 40 years ago and if you cant see a fucking tractor running second to a water truck down the stretch, it is time to hang them up. Not saying the drivers would have heard him, but like with loose horse on the track you have to give it a go,