This episode marks the first use of the term "fringe science" in a J.J. Abrams production. Six and a half years later, the Abrams TV series Fringe (2008) would begin its 5-year run.
Part of the setting inside 'the Vatican' when Sydney and Vaughn are looking for the painting is recycled from an earlier episode, Mea Culpa (2001). The spiral staircase from that episode is recognizable.
This episode takes inspiration from The X-Files (1993), with the section dedicated to supernatural events and fringe science. It even includes its own version of Cigarette Smoking Man.
Number 47 is visible on the box where Sydney and Vaughn find the code key is labeled 14547.
Lindsay Crouse and James Handy previously worked together twenty years earlier in The Verdict (1982).