I agree with Stahl on the Viper.
Something happened to lock the rears up.
In a kart, it would be like "sticking" the motor at the end of a straight: rears lock and you're around faster than you can blink.
I think it happens way too suddenly to be an overzealous trail-brake situation.
Also, I don't think it was a "money shift," as when I think of that, I think of it happening during an upshift.
It was either a mechanical failure (but there's no smoke) or a botched downshift like Stahl suggested.
Off to the GTO...
If you're in control, you're not driving fast enough -- Parnelli Jones