Factual error: The group of Japanese soldiers who came to Cabanatuan following the guards desertion were not "secret police" with orders to execute the POWs as shown in the film. They were simply units who happened to temporarily halt at the camp during their retreat from the advancing Americans.
Factual error: The plane used in the flyover to distract the Japanese from the approaching Rangers was not the B-34 Ventura shown in the film, but rather the P-61 Black Widow night fighter. The latter was specifically chosen because it was an unknown, rather strange looking plane that would attract maximum attention and be psychologically unsettling to the Japanese.