This was the most expensive Chinese film ever, with a budget of $135 million and, due to the huge amount of crew involved, had over 100 translators.
For his role as an archer, Matt Damon was trained in Hungary by Lajos Kassai, a world-champion archer.
The filmmakers were denied permission to film on the actual Great Wall, so the locations were added digitally.
The colored mountains in the film are real. They can be seen in Zhangye in the northwest region of China.
The beasts in this film are called the Tao Tei, named after an evil fiend in Chinese mythology. Here they are represented as alien beings.