When Shiwan Khan and Lamont Cranston first meet, their dialogue about where Cranston purchased his tie is a spoof on product placement during the radio airing of The Shadow.
What attracted Tim Curry to this project more than anything else was the chance to work with Sir Ian McKellen.
The Shadow (originally played by James La Curto, and then famously by Frank Readick) made his debut on radio in 1931, as the third-person narrator of mystery stories on Street & Smith's Detective Story Hour. When fans of the show wrote in asking for adventures starring The Shadow, Street & Smith hired Walter Gibson, a magician and former ghost writer for Harry Houdini, to write a monthly series of pulp mystery novels. The Shadow Magazine ran until 1949, and was the most successful pulp series ever. Beginning in 1937, The Shadow starred in his own radio show, originally featuring Orson Welles as Lamont Cranston and Agnes Moorehead as Margo Lane. Other actors later played The Shadow on the radio show, which ran until 1955.
Sam Raimi originally wanted to adapt and direct this movie, but was denied the rights to it. He made Darkman (1990) instead. Raimi tried again to make a Shadow film with producer Michael E. Uslan in 2006, but the project never got off the ground.
The billboard of the "Smoking man" is a parody of a real one that actually blew "smoke" rings. The original was for Camel cigarettes, whose motto was "I'd walk a mile for a Camel!" The "Llama" cigarette motto parodies this with "I'd climb a mountain for a Llama!"