During the skirmish in the hallway, the Japanese troops would have used bolt action rifles; most probably the Arisaka Type 99 or Type 38. But, the troops' rifles have no handles on their bolts, and one soldier even fires twice without mechanically chambering another round.
The fidelity of the props to the setting of Japanese Empire in Korea during the late 1930's is actually quite impressive. However, one detail kept cropping up over and over, and that is the intravenous (IV) equipment. What I see are spiked drip chambers using clear plastic and topped by white plastic spikes. Plus, the fluid runs through clear IV tubing regulated by white plastic roller-type flow regulators.
These did not exist in the '30's.
The standards of the time utilized rubber "surgical" tubing, metal thumb clamps, and rate controlled by eyeballing fluid volume administered over a given time, such as 4 ounces per hour. This would be read off of a scale printed or cast molded onto the side of the bottle.
Japanese soldiers arrive in a US Jeep and two US Vietnam era two and half ton trucks.
Small tape recorders like that shown in the film didn't exist then.
The Japanese officer uses the German Walther P38 pistol. It's mass production began in mid-1940. The Nambu pistol is the gun that Japanese Army was using in 1938.