Goofs

As various different characters observe the approaching tsunami, the wave appears and disappears before its final strike.

(at around 17 mins) As Heather is receiving the radio complaint about the parasailer, there is a shot of her covered in blood, before the incident even occurs.

After the sharks are discovered, it is repeatedly stated that they have not existed in millions of years. In fact, goblin sharks live in very deep water off Japan. So far the largest specimen recorded is 14 feet, but little is known, including how large they get because they are very rare and live very deep, evidence shows at least 750 fathoms (4500 feet) deep.

A character kills a shark with a flare. Instead of eating the carcass, another shark focuses on trying to get into the lifeguard hut.

After the tsunami has hit, the water level on the outside of the lifeguard shack is just a couple of inches below the windows. But when we look at the characters inside the shack, the water level is only about a foot deep. This indicates that there is a difference in water levels by about two feet between the inside and outside water levels.

While evacuating the hut, the last character hangs from the skylight while holding down a box with his feet. He would have been better standing on the box and pushing against the ceiling to help keep the box in place, only gripping the skylight to exit the hut at the last possible moment.