The Japanese ships were too lightly constructed to support cannon fire, and they relied on boarding and grappling tactics, and moving troops to land quickly.

The Koreans had slower, more heavily constructed ships which mounted their best artillery pieces, and they used standoff artillery bombardment to sink the Japanese before they could approach.

I didn't see the movie, but from the previews it probably added a lot of bad history in the form of face-to-face sword fights and hand-to-hand combat, when the real tactics were to stand off a few hundred meters and destroy ships with artillery, and to rely on tidal currents and lack of maneuvering room to entangle the Japanese ships with each other.