Trivia: A scene in which Sebastian brutally and graphically rapes his neighbor was filmed, but was mostly deleted as test-audiences felt it made Sebastian far too evil. And thus, the version of the scene in the theatrical cut only alludes to the idea without directly showing it. The original scene was reinstated in the director's cut released on DVD and Blu-Ray however.
Trivia: Whenever Sebastian is invisible and interacting with the other characters, Kevin Bacon's voice would be broadcast throughout several speakers randomly hidden throughout the set. This was done to make the reaction more genuine, since the actors would honestly not know where his voice was going to come from next, just as the characters would not know where Sebastian was.
Trivia: The infamous scene where Sebastian kills a dog was thoroughly investigated by the ASPCA - a non-profit animal welfare advocacy group. They reportedly felt the scene (despite being only shown in heat-vision footage) was so graphic, they suspected it might have been real. Director Paul Verhoeven ended up having to demonstrate how the scene was accomplished - star Kevin Bacon picks up a real dog, but through some slight trickery, was able to quickly switch it out with a realistic fake dog filled with stage-blood when he goes out of frame for about a second.
Trivia: Director Paul Verhoeven made the film because he wanted to make something more mainstream and palatable for wide audiences, given the overt violent nature and satirical tones of his previous films. He later stated that while he enjoyed working on the project, he feels it was a mistake because it wasn't a film that challenged him or spoke to his sensibilities, elaborating: "I think many other people could have done that. I don't think many people could have made RoboCop that way, or either Starship Troopers. But Hollow Man, I thought there might have been twenty directors in Hollywood who could have done that."
Trivia: The pool scene was one of the most complex to shoot, as traditional green and blue outfits didn't have enough contrast to be practically "keyed out" (aka removed digitally), as was done with other scenes due to the color of the water and background. Kevin Bacon's entire body ended up having to be painted pitch-black, as it was the only color to provide enough contrast for the digital artists to be able to practically remove him from the scene without having to go through and do so frame-by-frame.