After all the auditions for 16-year-old Quinten were done without much success, Jeroen Krabbé stared out of the window and Neil Newbon happened to pass by. "That's what Quinten should look like" he mumbled, not yet knowing the guy was an actor.
While in Cuba, Ada gives Max a necklace bearing a cross, a crescent moon and the star of David, the symbols of Christianity, Islam and Judaism respectively. Quinten can be seen wearing it later on. It foreshadows the final act of the movie, which takes place on the Temple Mount in Jerusalem, a place sacred for Christians, Muslims and Jews.
In the novel, while in Rome, Quinten visits the Arch of Titus on the Via Sacra, which depicts Emperor Titus' army bringing the spoils from the Temple of Jerusalem back to Rome. Quinten identifies a figure on the side of the monument, holding what seems to be the Stone Tablets, which is how he becomes convinced the tablets are still in Rome. Although this part of the book was left out of the movie, the Arch of Titus still makes a prominent appearance when the camera pans over the Via Sacra.