An anatomically correct, totally working computer model was created of Kevin Bacon's entire body - down to the last capillary. The 3-D model has since been donated to scientific researchers.
Director Paul Verhoeven and director of photography Jost Vacano had to be informed on set as to what Sebastian's 'Marco Polo' taunt meant. As Verhoeven is from the Netherlands and Vacano from Germany, neither had ever heard of the game.
During filming, Kevin Bacon wore skin-tight costumes in green, blue, grey, or black, to assist with the adding of visual effects. Some of his cast mates said that the hardest part of the role was not laughing at someone painted in black, green, blue, or grey, pretending to be mean.
To get the right reaction from the cast, Paul Verhoeven had speakers put in different places on the set, and had Kevin Bacon's voice come from different speakers so the cast would genuinely react to the invisible character moving around. For the scene with the invisible gorilla, Verhoeven screamed to the microphone, imitating gorilla noises.
When the crew carries a half-invisible Sebastian back to the operating table, a metal skeleton was used. It was made of metal in order to make it heavy, so the actors would give the impression of carrying a human body.
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.
Despite assumptions that Bacon would not be needed on set, except when his character Sebastian is visible, Verhoeven and the crew realized after test footage was shot, that he would need to be present, to interact with the cast, as "the other actors were stranded in empty space, and the scenes looked stiff, inorganic, and unconvincing" without him.
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".
In order to use the title, producers bought the rights to Dan Simmons' novel "Hollow Man". The novel has nothing to do with invisible men.
Creature effects supervisor Tom Woodruff Jr. played the gorilla Isabel, similar to the alien roles he played in the movies Aliens (1986), Alien³ (1992), and Alien: Resurrection (1997). To obtain a picture in the heat-sensitive infrared light, crew members warmed up the fur of the gorilla suit with hair dryers.
This is the first Hollywood movie of Paul Verhoeven that got an R-rating in its first submission to the MPAA. His previous American films, RoboCop (1987), Total Recall (1990), Basic Instinct (1992), Showgirls (1995) and Starship Troopers (1997) initially received X and NC-17 ratings, of which all except for Showgirls were re-cut to receive an R-rating.
Paul Verhoeven was dissatisfied with the film. In 2013, he remarked to The Hollywood Reporter: "I decided after Hollow Man, this is a movie, the first movie that I made that I thought I should not have made. It made money and this and that, but it really is not me anymore. 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. I felt depressed with myself after 2002." In earlier interviews, Verhoeven explained that the job was offered in a period where many of his proposed movie projects had fallen through, and he accepted to stay in business.
Guy Pearce and Edward Norton were considered for the role of Sebastian. Kevin Bacon was chosen for his "ability to be both charming and diabolical".
Because of the graphic nature of the invisibility transformation scene, one trailer that included the transformation was given Mature Audiences rating by the MPAA and was allowed to be played only before R-rated films.
Besides the full body suits in different colors for visual effects scenes, Kevin Bacon also had to wear full-eye contact lenses the same color as the suits for most scenes.
Shooting was delayed while Elisabeth Shue recovered from a torn Achilles tendon sustained during filming.
Most visual effects shots involved up to seven different plates. In most cases, one plate consisted of an empty shot of the scene background, where the movements of an invisible Kevin Bacon were later matched.
The tranquilizer guns used in the beginning are in fact PGPs, an early model paintball gun.
Kevin Bacon kept a journal during production for an article in Entertainment Weekly. Among the little info bits related to the filming: Bacon's most challenging aspect of the FX involved in playing the Hollow Man was keeping his outfit with little tennis balls on it from getting disordered; Paul Verhoeven gave the crew four days off in September 1999 so that Jewish cast and crew members could observe the Yom Kippur holiday; and Bacon's daughter faced a terrifying health crisis but after a few days recovered fully.
Because of the graphic nature of the layer-by-layer invisibility transformation, some production publicity photos indicated a different type of transformation. One particular publicity photo had Kevin Bacon invisible from the chest down, with the remainder of his body being fully visible, which contradicted with the transformation in the movie where one layer of his body become invisible exposing the underneath layer.
Two-thirds of the 560 visual effects shots were completed by Sony ImageWorks effects house, while the remainder was done by Phil Tippett Studios.
Filming was shut down for seven weeks after Elisabeth Shue tore her Achillies tendon during filming. The producers thought about replacing her, but chose to postpone production instead.
When Sebastian and Linda are talking about their past relationship, she mentions time travel as a metaphor. Real time travel and invisibility with a dark side, are major themes in two of the best known H.G Wells novels, one of which inspired this movie.
When Linda and Sebastian are talking out on the balcony, Sebastian asks Linda, "You ever thought of turning the clock back and trying again?" Linda replies, "I'd say that kind of time travel doesn't exist." This could be an homage to Elisabeth Shue's role in Back to the Future Part II (1989) and Back to the Future Part III (1990).
Isabelle, a member of a normally herbivorous race (gorillas), messily devouring a rat while under the invisibility serum foreshadows how much the serum is really a psychotic serum and the corrosive effects it would have on the human mind.
This is the second film where Kevin Bacon is shown nude. The first film is Wild Things (1998).
Kevin Bacon and Josh Brolin later appeared in comic book adaptations. Bacon starred in X-Men: First Class (2011) and R.I.P.D. (2013). Brolin starred in Jonah Hex (2010), Men in Black 3 (2012), the Marvel Cinematic Universe, and Deadpool 2 (2018).
The film was nominated for the Oscar for Best Visual Effects along with Gladiator (2000) and The Perfect Storm (2000). It lost to Gladiator (2000).
This film is the third Paul Verhoeven directed film that was nominated for the Oscar for Best Visual Effects. The first two films are Total Recall (1990) and Starship Troopers (1997). Total Recall (1990) is the only Verhoeven film that has won the award.
Kevin Bacon wanted the role of Dr. Sebastian Caine badly because he really wanted to portray an invisible man whose own morality decreases.
About 20 years after the release of this film, The Invisible Man (2020) was released. Both films are mostly based on H.G. Wells' story, "The Invisible Man".
The defibrillator used on the set is a MedTronic Physio-Control LifePak 8 defibrillator.
Three of the Elevator Authorization codes were: Caine, 0-0-2-7 McKay, 1-Delta-8-3-5 Kensington, 2-Romeo-1-5-9 At first the elevator replies, "Confirmed", but, later, when Dr. Sebastian Caine erases everyone else's codes, the elevator replies, "Authorization Invalid-Request Denied."
Both this film and The Invisible Man (2020) feature lead actresses with the name Elisabeth and a four-letter surname: Elisabeth Shue in this film and Elisabeth Moss in The Invisible Man (2020). Both actresses are blonde and were both also 36-years-old at the time of the filming of their similar films.
The small two-way radios the crew uses toward the end of the movie are Alinco "ham" radios, possibly DJ-C5Ts.
Caine tells a well-known joke about Superman and Wonder Woman, with the Invisible Man note caught in the middlenote. Possibly subverted, in that no one laughs. It only acts as foreshadowing of Caine's character.
This film marks the first time that Kevin Bacon portrays a character whose first name is Sebastian. The second time is in X-Men: First Class (2011). In this film, he portrays Dr. Sebastian Caine. In the latter film, he portrays Sebastian Shaw. Both characters are villains.
This is one of the two films that starred Kevin Bacon released in 2000. The other film is My Dog Skip (2000).