Steve Guttenberg was offered the lead role of Fin Shepard, but turned it down. When the film became a cult hit, Guttenberg regretted it to the point that he accepted a role in Syfy's Lavalantula (2015), a movie about giant fire-breathing tarantulas that attack Los Angeles.
Homage to Steven Spielberg (director of Jaws (1975), the icon of shark phenomena in films): when the shark is on the Santa Monica pier and attempts to attack, they shove an air tank into its mouth to blow it up. That's how the shark in Jaws was finally killed. The second is in the same scene with the ferris wheel rolling down the pier - an homage to Spielberg's not-so-successful film, 1941 (1979). Third is when a shark lands in front of Grauman's Chinese Theatre, it falls just behind the sidewalk square with Spielberg's signature and handprints in cement. Fourth: When Nova and Matt go up in the helicopter and come up against the first tornado, Nova exclaims "We're gonna need a bigger chopper!" The original line in Jaws is "We're gonna need a bigger boat!" Fifth: Nova tells a similar story to Quint's tale of the Indianapolis sinking, even stating how many men were in the water and that the "sharks took the rest." Sixth, people run from the loose Ferris wheel like Indy ran from the boulder in Raiders of the Lost Ark (1981).
Many crew members became sea-sick during principal photography, as well as one of the actors. So not everything could be filmed at the time, hence pick-ups were needed. A lot of the pick-ups were done with the boat at dock so as to not get talent or crew sick again.
Tara Reid's character's house was a combination of three locations. The wide effects shots of it raining and sinking were done with a house found on the side of a street. When the car drives up and the heroes get out, it's a mansion with rain towers set up for the storm effect. And then the interiors were a set built in a pool so it could be flooded.
The opening sequence at sea looks like it takes place on one boat but was actually two boats. They filmed on a sailboat for one day during principal photography. The film needed pick-ups and they rented a cheaper boat to double for the hero boat. You can tell they don't match in certain shots as the original boat was longer and had a mast and large ships wheel.
Director Anthony C. Ferrante originally wanted to use exclusively practical effects for the film, but was forced to revert to CGI due to budgetary constraints and because an extra's head was eaten by a falling shark.
One of the choppers used, or at least the interior, is registered in Australia. During one of the in-cabin shots, the registration, starting with "VH" (the Australian code) can be see on the centre of the black instrument binnacle.