Other mistake: When the Japanese planes take off for Pearl Harbor, some of the 3 man torpedo planes only have a pilot.
Deliberate mistake: There are no lights ever to be found in the underground world and the ceiling is literally the surface's ground, but there is still a perfect level of lighting regardless.
Revealing mistake: Blank firing adaptors are visible on the bow machine guns of Oddball's Shermans as they shoot up the rail yard. (01:00:05)
Revealing mistake: The cannons shown are firing blank charges, which produce no recoil. Recoil has been simulated by towing the guns backwards when they fire. The problem is, there is always a distinct delay between the discharge and the "recoil." The cannon also seem to largely fire explosive shells. At no point do we actually see a cannon ball rolling or bouncing along the ground or into any group of soldiers.
Other mistake: In the opening credits, character actor Andreas Malandrinos has his last name (as it happened not infrequently throughout his career) misspelled as "Melandrinos" (00:02:55)
Continuity mistake: In bed, the paper bag Iris gives to the cop has holes in the part of the bag that has no logo. In the corridor, we see his facial features pop from the side with a big green thank you circle. (00:31:50 - 00:32:30)