Kentucky Blue Streak (movie, 1935)

A nosy reporter (Nugent) befriends the dumb Coughlin and pushes the Governor to commute his sentence. Now, Coughlin can ride his family's pride and joy in the Kentucky Derby. BUT, the mean old Warden cancels all paroles--and the idiot decides to escape (even though he's only got 10 more months to serve). So, the reporter has a hunch and goes to see if he can find Coughlin--and the Warden deputizes him!! At this point you might wonder if the boy will make good and win the big race