The flashback scene in which Christian Slater is becoming invisible re-uses footage from the original Hollow Man (2000).
When Jack and Maggy are walking on the sidewalk, a man is heard shouting "Bacon is murder!" The part of the homicidal invisible man in the original Hollow Man (2000) was played by Kevin Bacon.
The prescription bottle Frank Turner places on Det Harrison's desk is labeled "Kindasortacyn" and its generic equivalent, "Somethinesleacyn".
The newspaper photo of one of the killed doctors is of Paul Verhoeven, the director of the first Hollow Man movie. The photo was taken on location while filming Starship Troopers (1997), but has been altered for its use in this film.
In this film, Christian Slater plays Michael Griffin. Griffin is the name of the invisible man in the novel The Invisible Man by H. G. Wells.
The character's name "Michael Griffin" is a direct reference to the character of "Griffin" from H.G. Wells' 1897 serial novel "The Invisible Man". In Wells' story, Griffin was driven insane by his invisibility - much like the character in this movie.
There were only 250 visual effects shots in the whole film, and 80 of them were simply wire removals.
During the final battle between the two Hollow Men, Turner kills Griffin with a shovel/spade. In H. G. Wells' The Invisible Man, Griffin is beaten to death with objects also including a shovel.