This movie along with RoboCop (1987), Basic Instinct (1992) and Starship Troopers (1997) is one of four separate movie franchises in which the first movie of their series (directed by Paul Verhoeven) were successful, but their sequels (not directed by Verhoeven) all either bombed at the box office or were released 'Direct-to-DVD'.
To achieve convincing visibility underwater in the pool scene, the effects crew made countless experiments with transparent objects and transparent molds of body parts underwater. In the end, the entire body of Kevin Bacon, including hair, was painted black for the scene because black gave the best contrast underwater.
Since the viewing goggles used infrared radiation for seeing invisible objects, they could not see through a metal locker. However, the woman in the locker was leaning against, and hence warming, the door, and its her warmth that was shown.
Numerous problems inherent to the "invisible man" premise are completely ignored. Some examples: Since light passes through the retina Sebastian would be blind. The soles of his feet would be visible from the dirt picked up by walking barefoot. The food he eats becomes immediately invisible.
This film is inspired by the novella "The Invisible Man" by H. G. Wells. The stories are quite different though, taking place in a different time period and a different place with a completely different series of events.
That being said, the basic premise of the movie is very similar to that of the book. A young, brilliant, but emotionally unstable scientist invent a way of becoming invisible. He tries it on an animal and then on himself, but can't become visible again (for different reasons though). Eventually this turns him crazy and evil, he suffers from delusion of grandeur and murderous rage. The protagonists have no choice but to kill him in self-defense. Certain small details are borrowed from the book, like using makeup and falling water to break invisibility (although in the book these methods are only discussed), and the fact that body becomes visible again after death.
Q
What are the differences between the Theatrical Version and the Director's Cut?
A
Being released as a Director's Cut nearly seven minutes of new footage were added to this movie. Most of these new scenes are story extensions but there are also two shots with added violence plus the rape scene was prolonged as well. A detailed comparison between both versions with pictures can be found here.