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 is a huge fan of the Phantom, having been introduced to the comics while filming Todesstille (1989). Zane has also called this his personal favorite film he's made.
The Phantom wears two rings, one on each hand. On his right hand, had he wears the skull ring that is most associated with him. It is the ring that burns a skull impression into those he punches. On his left hand, he wears what is know as the seal of the Phantom. The Phantom gives the seal to those he forms close friendships with. He is then honor bound to help anyone with the seal when they are in some sort of trouble.