Jet Li was originally considered for the role of Eddie Chan. While the film was still in pre-production, his agent Jim Choy was gunned down by the Triads. The incident caused Li to opt out of making a movie about organized crime, as he was afraid of attracting the wrong attention, so he chose to do Tai-Chi Master (1993) instead.
Allegedly, the original script was even darker, with Eddie Chan being emotionally damaged, in a love-hate relationship with his therapist, and having considerable self-doubt. These things, which had attracted Chan to the role in the first place, apparently made him worried about how it would affect his screen persona; as such, many scenes were removed from the final film and new ones added to lighten the tone, to the chagrin of director Kirk Wong.
Rumors that Kirk Wong and Jackie Chan did not get along during filming are just that: rumors. On the Dragon Dynasty DVD commentary, Kirk explains that he and Jackie got along just fine. He did, however, express disappointment over the fact that Jackie had made several cuts to the film without his approval. He goes on to say that he and Jackie have never spoken since the film's premiere.
Inspector Eddie Chan was originally in a romantic relationship with his therapist, and a few scenes were filmed around this subplot, but cut from most versions of the film. The Singapore version has these scenes, one of them constituting a slightly extended ending.
Loosely based (as acknowledged in most versions) on the real story of millionaire Teddy Wang, who was kidnapped twice, first in 1983 and again in 1990. After the second kidnapping he was never found (in most versions of the film he is thrown off the kidnappers' ship, which is allegedly what really happened) and in 1999 he was officially declared dead.