At about 1:21, the sailboat is shown passing the starboard side of "AKA 94". The next scene shows the sailboat coming about and the nearest ship is far in the distance.
The shot of Landing Craft PA-11 is seen twice during the first beach landing. The troops exit in exactly the same manner, including the soldier who runs to the immediate right of the craft.
About a third of the way through the film, the Belinda is shown taking part in the assault on Makin Atoll. Numerous hilly and mountainous islands are seen. However, in real life Makin is extremely flat.
Commander Quigley is given command of the APA Peacock. There was no USS Peacock during World War II.
When the boat rocks back and forth when the officer explains why the floors in the mess hall are waxed, there is an external shot that shows the boat and the ocean, the horizon moves with the boat.
When the men are reading their mail, many of the "letters" are blank paper.
Just before the crew begins to seal the hatch to make an air bubble, light can be seen reflecting off the water deep in the hold. For this to happen there would have to be an above water opening in the side of the ship, which would make an air bubble impossible. However, the hold is obviously a stage setting with lights above the water to make it visible.
In the opening sequence, the off-screen narrator tells us the year is 1943, and immediately a post-WWII 1946 DeSoto taxicab pulls up center screen.
(at around 1h 28 mins) During the final battle, a crew member holding a cable is seen behind Captain Hawks.
Lines are visible towing models of Japanese planes several times during the final battle sequences.