This movie is credited with creating the "aluminum foil hat" for paranoid conspiracy people.
One of two 1983 romantic comedies in which Dudley Moore starred with the other being La fille sur la banquette arrière (1983). Both pictures shot in New York City. Moore's then recent movie Arthur (1981), which had been a box-office success and garnered several Oscar (Academy Award) nominations, had been filmed in New York.
The clinical term that Sigmund Freud (Sir Alec Guinness) described Dr. Saul Benjamin (Dudley Moore) as was "nutsiefagen". This is a real joke slang clinical term, but spelled differently to the DVD's subtitling spelling. Urban Dictionary says "Nutsy Fagan" is "when someone is in a situation with another someone who is acting completely out of sorts (nuts, loony, berserk) and can sometimes, if successful, make the people around them embarrassed or disgusted."