The national markings of the American transport plane shown near the end of the movie (1945) have a red dot in the middle of the star. That red dot was deleted from American planes in 1942 to avoid any possible confusion with the "hinomaru" red circle used by all Japanese planes.
There is a modern white dress with a modern "invisible" back zipper when Louis is taken to lunch in downtown Tokyo. She is sitting behind him with her back turned and you can see it a few times when the camera pans to Louis. Long center back zippers only became commonly used in the 1950s. Invisible zippers didn't come into use of clothing until much much later.
When Louis departs for the 1936 Olympics, he boards a train consisting of wooden passenger cars with open platforms. By 1936, virtually all passenger trains had steel cars with enclosed vestibules. The train used in the film would be more correct for the 1890s.
The US transport that delivers Zamperini at the end is a Lockheed Electra with Australian civil markings. Furthermore, the non-regulation stenciling on the nose says "Army Air Corp" when the Air CORPS became the Army Air Forces in 1941. The military "serial" is the current Aussie registration, VH-HID.
Watanabe used English to order his soldier to shoot Zamperini if he dropped the log. The order should have been in Japanese since throughout the film it seemed that only Watanabe and the radio representatives could speak English. It is also unlikely as he is talking to a fellow Japanese, who would undoubtedly understand him better with Japanese.
In the first scene where the B-24 is shot up the co-pilot says we have no flaps, pretty soon we'll have no brakes. The runway is 6000 feet and we're going to need over 10,000 feet." At the approach and landing speed of that aircraft they wouldn't need anywhere near 10,000 feet to land. Also, the scene where they are landing, the runway looks to be about 3,000 feet at the most.
There never was scheduled passenger service by steam train to Torrance, CA, as depicted in the movie. There was service on Pacific Electric, but you'd have to show overhead electrified wires. He may have in real life started his journey on a long-distance train in Los Angeles.
The tail gun position on the B-24D Liberators are incorrect. In the film, it is an integrated open-tail mount, with a single hand-held .50 caliber machine gun. In real life, this position would have been a modified glass turret with a twin-.50 gun mount.
The B-29 Superfortress bomber that flies overhead as the POWs are standing in the river has a "Star and Bars" US national insignia on the underside of each wing. That insignia is actually painted only on the surfaces of the upper left and lower right wings.
At the end of the movie, in the prison camp, there's a squadron of US Bombers flying over the camp, one of the prisoners yell's "They are B-49's" The bombers were B-29's as the B-49 was an experimental plane who made the first flight in 1949.
Watanabe was a corporal, later a sergeant. So he was no officer at all, and could not possibly be "commanding officer" of a POW camp. He was very low ranked in the camp hierarchy and by no means the head of it.
The Japanese flag flown during World War 2 is the "Rising Sun". All instances in this movie indicate the flag flown is the modern Japanese flag with a red sun in a white background. This would NOT have been flown during World War 2.
In the coal yard where Louis was forced to pick up the lumber timber, at one point when Watanabe ordered his soldier to shoot if he dropped it, it was clear that the lumber is fake; and it's more like made of paper than timber.