Definitely going too fast.  The driver was 16, and from the reports, the right brake was hot and the left not.  Tractor is a John Deere 60.

https://youtu.be/4zoP2stRPsM?si=sK-MhHNL7vJ13hBA

Young, inexperienced and poorly trained operator that should never have been entrusted with a wagon load of hay, let alone people.

Tractor should have been in gear and clutch engagged.

Yes, tractors of such design sometimes pop out of gear with overhauling loads, but operator should have been so instructed if any down slopes on route.

Here there use to be a "Bring your tractor to school day" Til one year a young man put his tractor in neutral on a hill to see how fast he could go (Was a 8n too), Lost control rolled and was killed, That was the end of that tradition !