Aunt Wu's style of fortune telling is called osteomancy. It has been practiced for thousands of years in China and has also been practiced in various regions around the world.
Avatar Extras states that Calm Man is based on a specific security guard at Nickelodeon Studios.
The traveler (Calm Man) encountered by the children wears a hat that may be inspired by the Chinese futou. The futou was worn for more than a thousand years.
The bells in Aunt Wu's fortune-telling room resemble bianzhong bells.