Factual error: Toshiro Mifune's character, Kikuchiyo, travels to the bandits' camp and steals one of their two remaining fuselock muskets. Shortly afterward, the bandits fire twice at the samurai within five seconds with their last firearm. A fuselock takes as much as two minutes to reload, prime, and fire.
Factual error: The giant squid's tentacles aren't shaped like ones in the real world are.
Factual error: After the plane takes off from Hawaii, bound for San Francisco, there's a long shot of it flying among the clouds, with the left side well lit by the Sun. If the plane is flying east, in the northern hemisphere, then the Sun would be in the southern sky, illuminating the plane's other side.
Factual error: In order to make Polyphem drunk, Ulysses and his men produce 'wine' by treading on grapes. Only thing is: without fermenting the stuff for a few months, all you get is grape juice, which is not even remotely intoxicating.
Factual error: Although the movie takes place in South America, the background jungle sounds include a bird called a Laughing Kookaburra. That bird is native to Australia and New Guinea, and not native to South America.