Factual error: After Pearl Harbor is attacked, all of the radios on the base are tuned in to Roosevelt's "day of infamy" speech. None of the radios were short-wave and FM wasn't widely available, so the likelihood of their hearing a live broadcast was slim to none.
Factual error: In the opening scenes at the base, a Jeep is shown driving around. While it is technically possible for one of Willy's prototypes to end up in China in early 1941, the particular Jeep shown had the vertical slot grille, not adopted by Willy's until 1942.
Factual error: The Japanese fighters that the AVG tangles with are Nakajima Ki27 "Kates" with a total of two 7.7mm guns. However, they are depicted in the film as having 4 wing-mounted guns.
Factual error: When Pappy tells Woody he is fired and to be on the plane out in two days, the camera pans to the desk calendar, showing Sunday, December 7th, 1941. Later, all of the AVG members listen to FDR's "day of infamy" speech. However, as far as China was concerned, being to the West of the International Dateline, Pearl Harbor was attacked on December 8th, and the speech occurred December 9th.