I'm not sure if many have noticed this, but I run in to it every day with my automatic. After the car has been sitting for a while (first start in the morning or first start on the way home from work), and I shift it into reverse, the throttle is very unresponsive and then causes the car to to jerk unexpectedly when I press it. As a result, it's difficult to reverse the car slowly because of the unresponsive throttle.
Steps to reproduce:
1. Start the car
2. Immediately shift into reverse
3. Press the throttle
*Keep in mind that if you don't see the loading bar on the screen, you haven't let the car set long enough to test this*
Oddly enough, after the car is put into drive (and has been running for a while), I can shift to reverse and the throttle is then responsive as it should be.