Regional flight during 72 hour Visa

I am flying from Taiwan to changsha and leaving from changsha to south Korea within the 72 hours. My question is this, I want to go to zhangjiajie during the two days I am there and I was wondering if I permitted to take a flight from changsha to zhangjiajie and back to changsha or do I have to take a train or a bus as part of the 72-hour rules and regulations