Cindy Low, Kate Goodchild, her brother Luke Dorsett and his partner Roozi Araghi all died when they were thrown from the raft once the water pump stopped working for the third time that day.
Ms Goodchild’s 12-year-old daughter and Ms Low’s 10-year-old son survived the incident despite also being thrown out of the raft.
Detective Brown revealed the water pump on the ride had stopped working twice in the hours leading up to the fatal incident, adding that no engineering staff attended the second time, and that the ride was simply reset.
Det. Brown said multiple safety recommendations such as the inclusion of an emergency stop button on the main control panel and the installation of CCTV footage for the unloading area operator were not implemented.
The inquest heard there were no sensors or guides on the ride for operators to determine when water levels had dropped to a dangerous point.
The court also heard that the Thunder River Rapids ride had a 'long history' of malfunctions, including an incident in January 2001 where several empty rafts collided and flipped over during a dry run before the facility was opened to the public.
In an internal email recovered from the time of the 2001 incident, a staff reportedly wrote: 'I shudder when I think if there had been guests on the ride.'
The inquest is ongoing.