If you were on the ride, I think the fear would be another car running into the back of you, hence the panic "stop the ride" shout. I'm amazing no one was filming it, the amount of videos online of the Smiler and the amount of people with phones on them, yet no footage of the accident as such.
Funny enough, the talk of the girl bleeding badly, I gave blood 3 weeks ago, it took just 6 minutes to lose a pint of blood through the needle. Amazed me how quickly your body can lose blood, so if she had open wounds, just goes to show how quickly someone could bleed to death.