The dead sailor harbouring a live crab, spooking Jammer out of his wits in the sunk submarine, is director James Cameron's younger brother Mike. The scene had to be shot several times to get it right, forcing Mike to hold the live crabs in his mouth, until the cry for "action", before releasing them. At one point he had to crush one with his teeth, as it gave him quite a bit of grief. Brotherly love immortalized.

The water tube that floats about was partially created with Adobe Photoshop, which was unheard of at that time. Adobe Photoshop had not been released to the public at that point. Submitted by manthabeat

Ed Harris had such a miserable time making the film that after it's release, he disowned the picture and refuses to talk about it.

The fictional company that owns and operates the undersea drilling rig is called Benthic Petroleum. In "Terminator 2," (also directed by James Cameron) after the escape from the mental hospital, our heroes hide out at a gas station. The pumps at the station feature the Benthic Petroleum logo.

When Bud and Lindsay are trapped in the mini-sub, he remarks that all he needs is a Crescent wrench to fix the leak.  Moments before, when trying to secure the underwater robot, he threw a Crescent wrench out of the way to get to a rope in a tool basket outside the sub. Did anyone else spot the irony?

Due to injuries he sustained during filming, Ed Harris had difficulty accepting a role in "State of Grace." Luckily, he was able to make that film.