From The Grindhouse Cinema Database
- Eric Braeden was originally cast as Paul Grogan, but he pulled out to pursue another project. He had already shot some underwater swimming footage which is used in the film.
- A waitress from the Holiday Inn where the director and crew were staying stood in for Heather Menzies during the topless shots because Menzies was concerned that her husband might not approve of the nude scene.
- This film was reported to have been shot in 30 days for $660,000.
- Bradford Dillman was originally unhappy with the characters' 2D nature, and asked writer John Sayles why his character was so thin. Sayles responded that Roger Corman regularly did not use good actors in his film, so he deliberately didn't elaborate on characters. But since Dillman was a "real" actor, he was more than happy to enhance his character's depth.
- This movie was one of the first efforts for effects and makeup artists Rob Bottin and Phil Tippet.
- Universal Studios attempted to sue New World Pictures for spoofing Jaws (1975). However, Steven Spielberg saw the movie in advance and loved it. After that Universal dropped the lawsuit.
- Ranked #9 on Entertainment Weekly's "Guilty Pleasures: Testosterone Edition" list (#927, March 30, 2007, as part of the article "Bloodbath and Beyond", about Grindhouse.) The magazine wrote, "After the success of Jaws, grind houses were overrun with schlocky underwater knockoffs. This one, directed by Joe Dante and written by John Sayles, is the best of the bunch."