Many scenes, like Harry (Samuel L. Jackson) and Norman's (Dustin Hoffman's) conversation about making up the ULF report and dealing with Ted (Liev Schreiber), were completely improvised.
Samuel L. Jackson would work on this film during the week, and then work on Jackie Brown (1997) on the weekends.
The jellyfish attack sequence used a combination of puppets, computer graphics imagery, and footage of real jellyfish, filmed at a nearby aquarium. The footage of real jellyfish was played at three to five times its normal speed, to make the jellyfish appear more aggressive.
Dustin Hoffman expressed some disappointment with the film. He felt it wasn't yet ready to be released when it was. There were many more issues that needed to be addressed, but they didn't have the time to cover them all. They had to deliver what they had, for the release date, which he felt was an incomplete film.
In the book, the sphere was supposed to be visualized as a "perfectly polished silver sphere" with "grooved convolutions" that acted as a door opening so that people could enter. The movie originally had planned to use a sphere that had the same qualities (perfectly polished and silver), but soon found out that if it was placed in a dark room, the reflection would look almost entirely black, and not as impressive. The special effects designer and director Barry Levinson eventually decided to go with a "champagne" colored sphere due to how it looked on-screen.
Barry Levinson: [Ralph Tabakin] Ralph (O.S.S.A. Official) has appeared in every Levinson picture from Diner (1982) to Liberty Heights (1999).