Deliberate mistake: When everyone is surfing at night, the sound of the waves in the background is significant, as it should be. However, at one point, when Keanu and Lori are having an intimate conversation on the water, the sound of the waves disappear. The wave sounds resume in the next scene.
Factual error: Australian police are never equipped like they are at the end of this movie. The 1st Police on the scene would be Constables, Senior Constables, Sergeants, & Senior Sergeants, & possibly plain-clothes Detectives from the Victorian Police Force. They'd be wearing their regulation uniform & carrying a regulation revolver & hand cuffs. The AFP *may* be liaising, but they're Detectives, too. No high-power weapons; no helicopters.