In the opening sequence, Annie and Bryan's wedding invitation is shown. It states that the wedding will be held on "Saturday October thirty nineteen hundred and ninety one." October 30, 1991 was a Wednesday, not a Saturday.
When George has a flashback about the house he just sold, he states that he remembers his first game of basketball with his four-year old daughter Annie. However, in Father of the Bride, Annie states while packing her room before her wedding, that she has lived in the house since she was five.
When George is telling the family that he has sold the house and Mr. Habib has offered him $15,000 to be out of the house in 10 days, when Nina says 'George!' she is looking across her left shoulder, when in fact, George is straight ahead of her.
Annie's name as shown on her wedding invitation, seen at the beginning of the film, is "Anne Elizabeth", but in Father of the Bride, we hear the minister give her name as "Anne Catherine" during the wedding ceremony.
There's a significant time discrepancy in the movie. Nina becomes pregnant during the "escapade in the kitchen," but by the time she starts feeling ill/concerned, nearly eight weeks has passed - two weeks before the termites attack, four weeks to sell the house, then ten more days to move out, then one more day before visiting the doctors. This is over 7 and a half weeks (assuming it takes 0 days to fumigate and put the house up for sale). This is a fairly unrealistic amount of time for a mature woman to begin questioning things. Then, at the doctor's George says they haven't done any thing for six weeks - to which Nina asks, "what about that escapade in the kitchen?" They're both quite off in their timing.
On the basketball court, they do a timeline montage. When Anne is grown and pregnant, George is wearing the khaki pants and tan sweater; when they go back in time to when Anne was 4 years old, he is wearing the same clothes. In the middle of the montage, when they show Anne as a teenager, George is wearing different clothes.
Early in the movie, George says the "trees were golden". Immediately after this, George is driving down the road and all the trees are green with the exception of one tree where the leaves on the bottom are just starting to turn.
Just after Nina finds out she's pregnant and she and George are discussing the whole thing, George asks if it could be a mistake made by the doctors. Not long after that, when they run into Franck, the nurse hands her the ultrasound image. Wouldn't George therefore have known that it was no error?
When George is holding his new daughter and grandson in the hospital the positioning of the blankets around the babies changes in the close shots and the wide shots. In one wide shot the baby boy's head is shown and it is obviously a plastic baby; the moving blankets is most likely to shield the plastic babies from the camera in the long shots.
In the scene where George is buying the house back, shutters are lying on the lawn. Towards the end of the same scene we see all the upstairs (there is no room on the lower level windows for shutters because of the trellis) have shutters.
Filming of the scene where George and Nina are in the car after she finds she is pregnant, took place in on Greenleaf Blvd, in Whittier. All the street scenes outside Nina's window on her side of the car are heading southbound. And All of George's passing scenery is heading northbound.
During the scene where George shows Nina his new hair and they are sitting on the floor, the water from the rain is dripping from the ceiling, when in fact they are in a 2 story house, so any water would drip from the upstairs ceiling not the downstairs.
When Annie moves in with her parents, George narrates that Nina was 4 weeks from her due date and Annie was 2 days passed hers. However, the due date given for Annie was July 26 and the due date given for Nina was Sept 4. If it is in fact 2 days after Annie's due date (making it July 28), it would be a little over 5 weeks away from Nina's due date - not 4 weeks as stated.
Mr. Habib pays George Banks $15,000 using $1000 bills. The US government had begun taking large denomination bills out of circulation in 1969, so the bills would technically had been part of a private collection and would have been worth far more than their face value.