In the scene where Cuba Gooding Jr. as Dorie Miller grabs a gun mount and starts shooting at the Japanese planes, look at the gun. It is an air cooled Browning .50 caliber machine gun, but the navy didn't use those until late 1942. They used the Browning .50 with a heavy water jacket instead.
For all its awfulness, this film is not a documentary. I'm sure that not many people who saw it are 1940's weapons experts. The plot has enough holes in it to fly a squadron through.
What else can we expect from a Jerry Bruckheimer production? It was a soap opera plot, with the attack on Pearl Harbor thrown into a special effects dominated film.