"The Invisible" is based on the Swedish film "Den Osynlige" (The Invisible (2002)), which was very loosely inspired by a novel of the same name by the Swedish writer Mats Wahl.
A subplot was removed involving drug smugglers. It was feared this would give it an R-rating and wasn't necessary to the plot.
The last film to be released by Hollywood Pictures before the label was completely dissolved by Disney.
The shirt that Nick is wearing at the end of the movie bears a crow on the chest. In some Native American legends (and the graphic novel by James O'Barr bearing the name) the crow could carry a person's soul back from the land of the dead.
When the researcher looks through Nicks room the day after the party, a copy of the book Catch-22 is seen on the bookshelf. The whole movie plot is about a Catch-22.