I think it was a race type shifter and he was having trouble operating it in panic mode. I'm not sure if ever got it shifted since some of those shifters need to have a gate lifted to move forwards. Neither guy thought of turning off the ignition. It sounds like they knew the throttle was stuck and had been riding the brakes but evidently neither guy thought about the next steps to take such as turn the ignition off, pull over, shift into neutral, shift into reverse, etc. Since they had not thought it out before then when panic hit they couldn't think so they just drove it into the back of a stopped car. The car might have had an emergency brake but neither guy said anything about it or tried to apply it. The driver panicked and drove it into a stopped car.