- Actor-Inspired Element: Samuel L. Jackson came up with his character's sudden death scene. Originally, he was given a lengthy speech, but both he and the FX team thought that the dialogue was absolutely terrible (his speech was apparently seven pages long in the script), so he asked them "You know, why don't you just kill me?" And thus was born one of the film's most famous scenes. He later called the head of the team and said "Best. Death. Ever!"
- All-Star Cast: The cast includes familiar faces like Thomas Jane, Saffron Burrows, Samuel L. Jackson, LL Cool J, and Stellan Skarsgård.
- Awesome, Dear Boy: Samuel L. Jackson happily signed on for the film, as he had enjoyed his experience working with Renny Harlin on The Long Kiss Goodnight.
- Based on a Dream: The story was conceived by Australian screenwriter Duncan Kennedy after he witnessed a "horrific" shark attack on a beach near his home. The tragedy contributed to a recurring nightmare of him "being in a passageway with sharks that could read his mind". This motivated him to write a spec script, while acknowledging the challenge of approaching a shark film without repeating Jaws.
- Big Name Fan: Stephen King is a fan of this film, believe it or not. Writing in People, King described the movie as the first he watched during his recovery after a near-fatal accident and claimed he "loved every minute of it".
- Cast the Runner-Up: Samuel L. Jackson was initially offered the role of Preacher, but his management didn't like the idea of him playing a chef and turned it down, so Renny Harlin created the role of Russell Franklin for him.
- Deleted Role: Ronny Cox shows up very briefly (in what's otherwise The Cameo in the finished film - he's not even credited) as the company partner and co-CEO of Russell Franklin in the beginning, and has no lines whatsoever. It is presumed that any dialogue Cox's character had was cut from the finished product.
- Deleted Scene:
- There was cut footage that made clear that the relationship between Dr. Whitlock and Janice was not only sexual, but that she was pregnant with his child. This was cut on the basis that it would have made Janice's death "not feel right", according to Renny Harlin.
- The film originally ended with Susan killing the shark and embracing Carter. After negative test audience reactions, this was changed to have her sacrifice herself to prevent the shark from escaping, while Preacher and Carter survived the film.
- Dueling Movies: With Lake Placid, both were aquatic animal-themed horror movies released in July 1999.
- Enforced Method Acting: For one scene, Thomas Jane had to swim alongside a real live shark. He was only allowed to shoot this once he had completed all of his other scenes.
- Executive Meddling: The film was originally set to end with Susan not only surviving, but delivering the fatal blow to the shark, before embracing Carter. However, during test screenings of the film, audience members were so incensed at Susan, who orchestrated the whole disaster and was unlikeable to boot, that they repeatedly yelled "Die, Bitch!" during the final act. As a result, the ending was reshot to have Susan perform a Heroic Sacrifice to stop the shark from escaping the perimeter fence, while her role was slightly toned down and Preacher's (LL Cool J) was beefed up to make him more of a heroic character.
- Prop Recycling: The orange colored mini-sub visible in the wet-entry area was the same mini-sub seen in the end of Sphere, also starring Samuel L. Jackson.
- Throw It In!:
- A somewhat dark example: the scene where everyone is running away from the water after the lab window breaks actually happened: the tank broke and the actors had to suddenly run away from three tons of water. The terror in their faces as they run for their lives is real. Renny Harlin decided to keep the footage in.
- Samuel L. Jackson improvised the Fantasy Island joke.
- Vacation, Dear Boy: In the DVD Commentary, both Renny Harlin and Samuel L. Jackson admit that the only reason the actor agreed to be in the movie was he got to golf between his takes (although Jackson also admitted he liked the prospect of reuniting with Harlin and being in a monster movie similar to ones he grew up watching).
- What Could Have Been: Originally, Susan was to be the hero of the film. However, after viewing the first cut of the film, Renny Harlin thought that her character was more or less the evil genius of the film, and had to be punished for it at the end. He purposely cut out some earlier scenes of Burrows to make her less sympathetic. It was also his idea to make Preacher the hero, citing that everyone liked him, and that he was a "pretty cool guy".
Trivia / Deep Blue Sea