In the restaurant scene, a waiter sits down to a piano to accompany the singing. While the piano is still playing, he is seen in the background waving his lobster arms.
Disappearing picture when Julianne is composing the email.
When Jules enters the private box at the ballpark, she is carrying a full tray of beers. She then hands a couple to some guys. A few seconds later the tray is full again.
After Julianne set up Kimmy to discuss with Michael at dinner the proposition of working for her father, Michael becomes upset and Kimmy burst into tears running down her cheeks, move to their kiss where her face is completely dry, then she pulls away from the kiss and she has tears again.
When George comes over to see Julianne, her cigarette disappears.
As Julianne exits the elevator, a 'license certificate' is seen on the wall. Elevators are 'permit'ted, not licensed.
Julianne has two pairs of sunglasses throughout the whole time she's at Kimmy's parents' estate, often wearing one pair while the other is hanging on her top button of her belly shirt. When she and Michael reach the gazebo and she takes off the sunglasses she's been wearing, one can see that she's holding two pairs.
Charlie Trotter plays himself in the movie. He is a Chicago chef and, at the time of the movie, had no restaurants other than his signature restaurant in Chicago. Jules reviews his New York restaurant; presumably, he was either hired away by a new fictional restaurant in New York or has opened a fictional branch of his Chicago restaurant there.
Scotty says he doesn't know who Dionne Warwick is. However, when the dinner party spontaneously begins to sing "I Say a Little Prayer" he knows the lyrics and joins in. This is not a "Goof" though, as people often know song lyrics from listening to the radio without having knowledge of the performer.
When George calls Julianne at the end of the movie, his mouth moves in perfect sync with the voice over the phone. In reality there would be a noticeable delay.
It's been pointed out that in 1997, it was illegal for a 20 year old to drink beer in a bar, as Kimmy does in the karaoke bar scene. However, between 1973 and 1979, 19 and 20 year olds were allowed to drink beer in Illinois bars. It's possible the screenwriter was aware of that when the script was written, but unaware the law had been changed since.
At the wedding reception when the cousins are singing "The Way You Look Tonight", the band leader can be heard singing backup vocals long before he steps up to the microphone.
When George drives Julianne to the airport to fly from New York to Chicago, road signs are seen for U.S. 45, Mannheim Rd., which is in Chicago.
After Michael and Kim pick up Julianne from O'Hare Airport, they're heading north on Chicago's Lake Shore Drive. Kimmy swerves wildly to her exit. The next time you see the car, it's heading south on Lake Shore Drive with the Drake Hotel in the distance.
In Chicago, Lake Shore Drive is bordered by Lake Michigan on the east and the city on its west side. However, in more than one scene when driving on Lake Share Drive, the lake is either on the wrong side of the vehicle, or it keeps changing sides of the vehicle.
The film depicts Jules' character departing from and arriving at the same airport. When Jules is flying out of what is supposed to be New York, she is shown being dropped and seen off at what is actually Terminal 5 at Chicago-O'Hare (Terminal 5 is O'Hare's international terminal). In the next scene, she is shown "arriving" at O'Hare's Terminal 1.
The boat ride magically teleports the characters to many different points along the Chicago River, from Lake Shore Drive to being alongside Union Station (trains in background) to Clark Street Bridge (Merchandise Mart in background).
During Title sequence, the lead Bridesmaid that is 'singing' messes up her words (toward the end of the song). You can see her quickly correct herself.
Kimmy is stated to be 20, yet orders an Amstel Light in the karaoke scene, even though this is forbidden by law to people younger than 21.
When Julianne is chasing Michael in the bread truck, she is talking on the phone and tells George that she is driving down Michigan Avenue. She is actually on Dearborn.
Kimmy is supposedly an architecture major at the University of Chicago, but it has no architecture program, although it has a minor in architectural studies.