The quote David utters in Dr. Alan Swinford's office, "When all at once I saw a crowd, A host of golden daffodils," is from the poem, "I Wandered Lonely as a Cloud" by William Wordsworth, 1807.
This film was shot on location in a building which has since been converted to St. Sahag & St. Mesrob Armenian Apostolic Church in Wynnewood, PA. Other scenes are at the Wynnewood train station and at the Philadelphia Museum of Art, where Keir Dullea runs up the same steps Sylvester Stallone runs up in Rocky (1976) 14 years later.
Box Office Magazine reported that such was the movie's success that private investors would get back $3,760 for every $312.50 invested.