The number that Adam dials in the movie is not a typical '555' movie number but rather is an actual phone number. At the time of the movie's production, the number rang at the home of the author of 'I Am the Cheese' and gave him an opportunity to interact with fans of the book and movie.
Only movie to feature real-life family unit (former spouses), Don Murray and Hope Lange, and their son Christopher Murray.
David Lange who produced and co-wrote the screenplay is Hope Lange's brother.
Robert Wagner and Hope Lange co-starred in "The True Story of Jesse James" (1957) and "In Love and War" (1958).