Billy Zane pumped iron for over a year to fill The Phantom's costume. A Batman-like costume with fake muscles was reportedly made, but by the time filming started, Zane was so beefed up that he did not need it.
Billy Zane shaved his head to get the Phantom's cowl to fit as close as possible. This necessitated all his scenes where he is out-of-costume with a full head of hair to be shot early in production. As a result, a scene where the Phantom removes his cowl was shot in two parts, in reverse order, several weeks apart.
Several scenes developing the romance between The Phantom/Kit Walker and Diana Palmer were shot in Thailand, but director Simon Wincer reportedly ditched them because he wanted the film to be more fast-paced.
Diana's idle-rich acquaintance Jimmy Wells (Jon Tenney) appeared in the earliest installments of the Phantom comic, when the Phantom was still a shadowy figure whose identity and motives had not been revealed. Lee Falk planned to reveal that Jimmy Wells was the Phantom's alter ego, and included several hints to that effect, before settling on the now-familiar backstory of the Phantom as a globetrotting crimefighter with a centuries-long heritage, and quietly writing Jimmy Wells out of the comic.
The story takes place in 1938/39 (just before the start of World War II). This is taken from the fact that Kit told Diana that it had been six years since they had last seen each other, and that Kit's father was killed by Quill in 1932, which can be seen on his tomb marker in the cave when Kit places the gun belt that he retrieved on it at the end of the movie. Another indicator of the year is the banner hanging at the entrance to the Museum of World History (it says 1939).
The Skull is a dominate symbol in The Phantom's life. He lives in the Skull Cave, he wears the Skull Ring, and in the movie, he was trying to find three Skulls. If you look closely at his costume, you will even see a skull design on it.
The Phantom's father (born 1872, died 1932), had he not been killed seven years earlier, would have been 67 years old in 1939 when the film takes place. Patrick McGoohan, who played the role, was also 67 years old when the film was made.
Loosely based on Lee Falk's first stories from The Phantom comic strip, "The Singh Brotherhood" and "The Sky Band". Screenwriter Jeffrey Boam added the elements of bad guy Xander Drax and his search for a weapon of doom.