Factual error: Why is Hilts not wearing a uniform? A serving officer captured behind enemy lines in civilian clothing risked being shot as a spy. If a prisoner's uniform was too worn or damaged to wear, it was routine for the German authorities to replace it - a P.O.W. in civilian clothes is an obvious escape risk. He is wearing a pair of tan chinos, a cut off sloppy Joe sweatshirt, both ridiculously anachronistic - Sixties hipster fashions - and nowhere even close to a World War 2 uniform. He is also wearing Army Type III Service boots - something that would never have been issued to a fighter pilot.
Factual error: The Forum shown in that film is smaller than in real life. Also, Cleopatra is shown passing through the Arc of Contantine, a monument that was built centuries after her death.
Factual error: Throughout the film, sea grape vines are seen all along the shore. Sea grapes do not grow in the Pacific, where the story takes place, only in the Caribbean where the film was made.
Factual error: The weapons for this film, save for the American Krag-Jorgensen rifles, British Lee-Enfield MLE rifles, and German Mauser Gewehr 98 rifles, are completely wrong. The Russians, who had Mosin-Nagants, are portrayed with Mausers. The French are for the most part correctly poratrayed with Lebel Mle. 1886/93 rifles, but a few have Berthier rifles that weren't used until 1907. The Austro-Hungarians are portrayed with a mixture of Mausers and Berthiers when they would have had Mannlicher M88/90's or perhaps Mannlicher M95's. The Japanese are equipped with Mausers and would in reality have had Muratas. The Italians have a mix of Berthiers and Mausers, but would've used Vetterli-Vitali rifles. The Chinese Imperial troops and Boxers both have Gewehr 98 Mausers. Although they did indeed have Mausers, they had the far earlier Gewehr 71's and Gewehr 71/84's.
Factual error: All of the PT boats in this film are painted in the same Navy Gray used by larger warships of the US Navy in WWII. However, the real PT 109 and the other PTs in its squadron were painted green in order to better blend into their daytime anchorages or moorings near island jungles. The common green color scheme of this period was designated as "Design 5P" and incorporated Navy Green over a base coat of Ocean Green.
Factual error: When Clay Spencer and his brothers begin work on his dream house, they mix and pour the concrete for the foundation, then immediately begin putting up the framing. The concrete would have to cure for at least two weeks before the framing could be started.