Just because a motocross competition is for children doesn't mean it's always safe. During a children's motocross race in Russia, one boy was walking back to retrieve his bike when another rider accidentally flew into the boy. The accident happened so fast almost nobody was ready to respond. Fortunately, the boy didn't suffer any life-threatening injuries and is expected to recover soon.
Speaking of accidents, sometimes you should just count your lucky stars and not tempt fate. We have a dashcam footage from a pair of motorcyclists who were pushing their bikes way above the speed limit, and one of them nearly experienced disaster. The rider ran themselves off the road, missing a telephone pole by inches, but was able to recover.