I almost crashed until I realized what was happening and put the car into neutral. (unfortunately, I overshot and put the car into park momentarily, which resulted in a slow leak of my transmission fluid that cost about $600 to fix).
Quick protip, since this is a pet peeve of mine: Automatic transmissions will shift from drive into neutral without the button pressed. This is to prevent exactly what happened to you. Also, you can shift from reverse into drive without pressing the button. Or even looking at the transmission readout, just slap it up or down, and you'll get where you need to go.
There are aircars, there have been for decades. They're called "helicopters". Sure they're expensive, noisy, use a butt-load of fuel, and you need a library of qualifications to fly one. But well, no-one ever specified any of that...
Aircar's and aircar.
Less weight = less inertia = greater accelerations upon the hard disk.
Depends what its running into. I'd figure the most common impact would be with things like tables and floors. And I can't imagine your floor or table will deflect significantly unless the heavier computer is the mass of a fridge.
A rock store eventually closed down; they were taking too much for granite.