William Holden was the original choice to star in the first film, The Omen (1976), but turned it down as he did not want to star in a picture about the devil. Gregory Peck was selected as his replacement. "The Omen" went on to become a huge hit and Holden made sure he did not turn down the part in this sequel.
David Seltzer was approached to write the screenplay but refused as he had no interest in writing sequels. Years later, he commented that if he had written it, he would have set it the day after the first The Omen (1976) film ended, with Damien living in the White House.
When Harvey Bernhard had finished writing the script and was given the green light to start the production, the first person he contacted was Jerry Goldsmith because of the composer's busy schedule. Bernhard also felt that Goldsmith's music for The Omen (1976) was the highest point of that movie, and that without Goldsmith's music this sequel would never be successful.
The Thorn Mansion is the Lake Forest Academy (formerly the Armour Estate) in Lake Forest, Illinois. All exteriors had to be shot in the back garden of the academy/estate because the school had erected a very modern structure in front of the old estate.
Don Taylor replaced director Mike Hodges as a result of creative differences. However, the few scenes Hodges directed were kept, like the scenes at the factory and at the military school, and also the dinner where Aunt Marion shows her concern about Damien.
"Davidson Military Academy" is really Northwestern Military and Naval Academy in Lake Geneva, Wisconsin, and has the same insignia. This school merged with St. John's Military Academy in 1995 to be St. John's Northwestern Military Academy in Delafield, Wisconsin.
Much of the film takes place at Davidson Military Academy which was started by the fictitious Harlan Page Davidson. The appellation "David's Son" is frequently used in the Bible to denote Jesus Christ, Damien's polar opposite.
The trivia items below may give away important plot points.
Lew Ayres performed most of the stunt of his watery death himself up until the point where his character disappears under the ice. Lee Grant tried to persuade the veteran actor not to do it but he was determined to give it a shot.