Factual error: When Harry and Sally are driving away from the University of Chicago at the start of their road trip there is a long shot of them driving on Lake Shore Drive, but they are heading south towards the city with the lake on their left. If they were leaving the city from UofC, which is in Hyde Park, they would already be driving away from the city on Lake Shore Drive.
Factual error: When Harry meets Sally for the second time it is on a flight in 1982. But the plane is a second-generation Boeing 737-300, the first of which entered service in December 1984.
Factual error: When Sally drops Harry off in front of Washington Square Park in Manhattan, the street signs are green with white lettering. However, street signs were yellow with black lettering in Manhattan during the 1970s - yellow street signs weren't replaced with the bright green ones used presently until the mid 1980s.
Factual error: In the classic Katz's' Deli scene Rob Reiner's mother tells the waiter 'I'll have what she's having'. One problem - Katz's is a cafeteria-style delicatessen; there are no waiters that come to the tables in the section where she's sitting.
Factual error: When Harry and Sally leave the University of Chicago to drive to New York, they pass through downtown Chicago on Lake Shore Drive, which actually would take them 10 miles out of their way.
Factual error: Their drive from Chicago to New York takes them through Wilmington, CA. There is a shot of the car going past a Genstar building. This is on the Harbor Freeway in Wilmington.
Factual error: At one point, on the University of Chicago campus, the main characters drive through Cobb Gate, the ornate Gothic gate at the north end of the university quads. Cobb Gate is now and has been for many, many years, closed to motor traffic.
