Driving up from Austin over the weekend in the right lane of 183. I had the car in autopilot. But in front of me slows down to make a right turn. I slowed down with him and my model 3 slowed down to a stop as he was turning. My car did not move out again after he turned. I mistakenly pushed on the brake instead of the gas. My fault there but when I realized my mistake and pushed on the gas the car still would not move. The car had placed itself in park. It took a few panicked seconds to realize this but then I pushed down on the stick and was able to drive away.