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 film ended, with Damien living in the White House.
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.
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 school which Damien and his cousin Mark go to, 'Davidson Military Academy,' has the same insignia as Northwestern Military and Naval Academy in Lake Geneva, WI where it was filmed. (Merged with St. John's Military Academy in 1995 to be St. John's Northwestern Military Academy in Delafield, WI.) The academy was started by Harlan Page Davidson and the academy was sometimes referred to as Davidson Military Academy.
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.
When the cadets are outside meeting Sergeant Neff for the first time, when the camera take a side shot of the sergeant, u see the leading drummer with the stick... there's something falling of the stick into the grass..
The trivia item 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.