Continuity mistake: In the final shot of Serenity leaving Regina near the end, the lights on the port (left) and starboard (right) sides of the ship are reversed - the port lights are green when they should be red and the starboard lights are red when they should be green.
Continuity mistake: After the opening credits River wakes up from a nightmare. She knocks over a rolling tray and some objects fall off it onto the floor. The position of the tray and the objects left on it changes between shots.
Revealing mistake: In the scene where Mal and Zoë exit the train, look closely at the woman in the yellow veil to the left of the screen holding a baby - she walks into a passing vehicle knocking her baby on its head (revealing it is really a doll).
Continuity mistake: When Mal is fighting Crow on the ship, he falls over the containers of medical supplies, knocking some of them over. A few shots later when Jayne shoots Crow, the containers are standing upright again.
Chosen answer: One of the premises of the show is that the two major Earth societies that survived, and ultimately merged, were the Chinese and Americans. As a result the common language includes much Chinese. Clothing, signage, and building designs also have a heavy Chinese influence.