I had shifted to 2 instead of D after backing up out of the parking lot, and shifted to D at around 60ish when I noticed the shift into 3rd didn't happen. All that happened was that the car found the next gear, no drama. However shifting into neutral is risky, not only due to what is stated above, but due to a pothole or carelessness, you might shift into reverse instead, and that's when the proverbial excrement will hit the fan. This had happened to a newish Nissan Caravan, my mechanic told me.