Factual error: In the opening shot of Union Square from above, all pedestrians have very long shadows. Later we learn that the action took place during the lunch hour. The sun should have been higher and the shadows shorter.

Visible crew/equipment: Gene Hackman's character has been listening at the door of Terri Garr's apartment. When he finally enters her apartment and she tells him she feels like he's somehow listening to her, the boom mike is visible in the frame in several shots in the scene.