Dzne, I can tell you how Carowinds and King's Island control their pedal-powered McBean-esque rides. While there are pedals they are also motorized. If you don't pedal they continue to move -- only slower. The track has various sensors along the path to automatically switch the pedal to the slower motor mode if the car in front of it hasn't cleared the next sensor.
Like McBean there is no emergency escape option. However, because of the pedals one can always pedal their way back into the station if there is any kind of power-usurping malfunction. Maybe someone more familiar with the Paramount parks can explain any evacuation procedure, but it's quite possible that an attendant might be able to pedal a car from the station all the way around the track to herd the rest of the stalled cars in. I don't know. I never saw a cherry picker anywhere near either park last summer.