Weird. I had a similar adventure as a 3 or 4 year old. I was at church with my family. It was an LDS church and whatever part of the service was last was of the type where we were separated by age group. So after my class was finished, I went to the parking lot to wait for the rest of my family. My dad's mustang was unlocked, so I opened the door and stood on the doorjamb with the door open so I was up higher and could watch for my family. Only the car started moving. My best guess is dad had it in neutral for some reason. It's possible I somehow kicked it out of gear, I guess, although I had purposely been avoiding touching anything in the control panel area.
So picture this... Little flourish standing on the edge of the car, door open, and car slowly rolling towards a somewhat busy street. Some other church goers see this and yell at me to jump off. But I'm having visions of getting crushed under the car and am frozen in fear. Luckily it wasn't much of an incline and the car stopped when it hit a curb and some bushes. Scary though! And this reminded me... Especially because mine was a mustang too.
I'm so glad this little gal is okay!