A scene was planned in the basement of the Odditorium and a sketch of the basement was made, but the scene was deleted.
Also a sequel was planned, called Ripley's Believe It or Not!: The Siberian Cipher, but it never made it past pre-production. Lee Sheldon gave an interview about the sequel to Just Adventure, which can be found in the related links section.
During production the device in the hidden lab in the "Ace of Spades" castle was called "The Gizmotron Device." The design of this device by Richard Hescox was made for a devilish puzzle that was created by François Robillard.
In the metal dealers alley in Peiping there's a sign with Chinese writing on it. It's a clue suggested by Richard Hescox (background design), and translated by one of the programmers, who was from China. The clue is "sekops eht esu" (spoiler, so written backwards).
The Master Lu box cover is based on a painting by Dave Kramer (Oil on Woodpanel, 13 x 14.5), who wasn't credited.
Originally, Peter Donnelly was the game's principle designer, and he developed the basic storyline and some of the puzzles. After his research, he became thoroughly sick of Ripley the man, and the result was that the design was taken over by Lee Sheldon and François Robillard.
If you open the game configuration file RIDDLE.CFG with notepad, you'll find the normal game settings along with some unusual ones, like REASON_FOR_LIVING=MOM'S APPLE PIE and PROGRAMMERS_SIGN=PISCES.
Some of the items featured in the game were actually real items that Robert L. Ripley collected for his museums and featured in his comic strips.