Jeff Fahey's character in Revelation entering an ultra-realistic virtual reality simulation is an allusion to his appearing in another movie featuring a virtual reality program where his character is warped to the point where he claims to be God. In contrast, Jeff Fahey's character in Revelation claims that he isn't looking for God.
Corbin Bernsen plays a lawyer character in Judgment, which is an allusion to his role in the TV series L.A. Law.
Old Shame: Margot Kidder didn't realize that Tribulation was Christian propaganda until she was nearly through filming. Apparently (and understandably) she didn't understand the plot until the end, when the Anti-Christ goes on a Motive Rant. Margot Kidder is an avowed atheist. People coming up to her and praising her work in said movie tends to be a Berserk Button for her.
The Other Darrin: Sam Bornstein played Franco Macalousso in the first movie, which was later played by Nick Mancuso in the following movies.