The original cut of the movie ran over 5 hours.
The film's Chinese release, set for August 2019, was canceled after Bingbing Fan was charged with tax evasion.
The film is based on the Japanese bombing of Chongqing, China, during World War 2. The bombing lasted 6 years and 10 months.
Jack appears to be based on Claire Lee Chennault, a former US Army Air Corps officer who became an air advisor and flight instructor to the Chinese government. Chennault later organized, trained, and led the Flying Tigers. In 1942, the US air elements in China were placed under his command.
The movie was made as a memorial for the 70th anniversary of the Allied victory in WWII.