During filming in Montreal, two local punk rockers with Mohawk hairdos were hired as extras for a scene in which they attempt to rob the newly awakened Kane in a dark alley. The two were paid a nominal fee, and thanked for their services before shooting. The scene was cut after they were seen taking drugs on the set and overheard plotting to kidnap Mario Van Peebles by driving away in the make-up RV with him in it.
Deborah Kara Unger did her love scenes with Christopher Lambert herself, declining to use a body double.
Although Khan's "Warrior #1" is never referred to by name on-screen, the script refers to him as "Khabul Khan."
Director Andy Morahan had directed several music videos for the band Guns N' Roses, and wanted them to do a soundtrack for this film similar to how Queen did the music in the original film. According to Morahan, they were excited about the idea, but it fell through when Axl Rose refused to do it if Mario Van Peebles remained in the film. The reason for Axl's dislike of Peebles has never been explained.
The film is true to the original Highlander (1986), and ignores Highlander II: The Quickening (1991). In Highlander 2, Connor, Ramirez and the Immortals were revealed to be aliens from the planet Zeist who were exiled to Earth (this was changed in the Director's Cut/Renegade Version of the film, where they come from a very distant past on Earth, and were banished to 16th-century Scotland). None of this backstory was suggested or even implied in the original Highlander, where Connor and Ramirez were neither aliens nor time-travelers, just humans who happened to be immortal. Highlander 3 takes place 8 years after the original film, and remains true to the original story and mythology.