During the battle scene at the blockade, Holman is send forward on the port (left) side with two men manning a BAR position. When the main battery on San Pablo fires and hits the mast of a junk, a group of men back aft near midships who are part of the boarding party are seen laughing, Holman being one of them.
When the San Pablo first gets underway Holman is wearing a clean set of dungarees, yet in the next shot when he is noticing an engine problem, he is wearing old, worn and dirty dungarees with no undershirt.
When Lieutenant Collins turns and faces aft to watch his men hurry to battle stations before the battle at the boom, the view shown is from the stern deck house looking forward, not what he is actually seeing from his position on top of the bridge.
During one of the scenes where the San Pablo is in danger of being boarded by hostile Chinese, the crewmen are issued Springfield rifles. But they are not given any ammunition belts. Even if the rifles were loaded, which they would not normally be while in storage, they would hold only five cartridges (six with a round in the chamber). Such a limited supply of ammo would not have been enough to turn back the large number of Chinese if they had attempted to board the ship.
At the fight at the boom,the cannon on the USS Sand Pebble has a recoil cylinder on top of the barrel but when fired, the barrel doesn't recoil. There is also no recoil shown for the muzzle loading cannon on the Chinese Junks.
There are several scenes in which Browning Automatic Rifles are being reloaded with fresh 20-round ammunition magazines. But the hollow sound made by the mags while they are being inserted indicates that they are empty.
The Machinist Mate First Class (MM1c) rate patch that Holman wears on his left shoulder is a post 1941-type where the "crow" faces to its right side. In 1926 when the movie is set, the crow on a Machinist Mate's rate patch faced left, looking away from the wearer's face. After 1941, all USN petty officer rate patch "crows" faced forward, like their wearer, to "face the enemy".
The goof items below may give away important plot points.
Just before shooting Po-Han with a Springfield rifle to put him out of his misery, Holman makes a long-range adjustment to the rifle's rear sight. Such an adjustment would not have been necessary, since Po-Han was fairly close to Holman.