One problem related to transmission stuck in gear has been reported for the 2010 Toyota Prius. The most recently reported issues are listed below.
My 2010 Toyota Prius would not start after a brief 45 minute lunch with friends. When I released the parking brake and let off the brake pedal I didn't know the car was stuck in neutral. This error was on the dashboard "malfunction when parking, park in a flat place and apply parking brake securely". When I let off the brake the car rolled back into the middle of the parking lot. I had two coworkers in the car with me; they got out and pushed the car out of the way to a flat location. Car still was disabled. I called Toyota roadside assistance and waited an hour for a tow truck; after about 45-50 minutes of waiting I was hit by a woman that wasn't paying attention; she backed into the side of my disabled car. I was pressing on the horn and she didn't hear. The impact must have freed some stuck component or something because 2 hours later when the tow truck finally came, the car worked again; no warning lights etc. Toyota looked at the car and says there is nothing wrong. I took a photo to document the warning message (plus have 2 witnesses).