The end of the film implies that the defenders fought to the last man; in reality, they surrendered after repelling the first wave of the Japanese attack. It also shows the garrison's naval commander dying of wounds and the defense of the island being directed by Marine officers; in fact, Commander Winfield S. Cunningham survived the war.
The film's opening credits state that the screenplay was written by W.R. Burnett and Frank Butler "From the Records of The United States Marine Corps", and includes many Marine Corps and military advisers. It also states that "In this picture, the action at Wake Island has been recorded as accurately as possible. However, the names of the characters are fictional and any similarity to the personal characteristics of the officers and men of the detachment is not intended." This is likely because the actual events were unfolding during the production of the film, and names were being protected.