Some of the flashback scenes, in particular those featuring Captain MacDonald's wife, Julie, are unrealistic in their depiction of the time period intended - namely early to mid-1940's. In particular, she is seen wearing her hair and mascara in a style that is clearly not of the mid-1940's, and in one scene, is shown wearing a blouse that is clearly of a mid-1960's design.
The Japanese have changed their uniforms to that of the Marines in order trick the Americans. When they are being strafed and bombed by American aircraft, there is a shot of 40 Japanese being shot. When they fall you can see that the extras in the back ground are wearing blue jeans and sneakers.