At the wedding, champagne is served in flute glasses, which were not popular and rarely used for champagne until the 1970s, when drier vintages became preferred; instead the champagne coupe (or saucer) glass was almost universally used for serving the beverage in the 1950s, and still is in champagne fountains at weddings.
During the slide show, Dr. Watson says "A Rhodes scholar. I wonder if she recites Geoffrey Chaucer while she presses her husband's shirts". Women were not even permitted to apply for Rhodes scholarships until 1977.
When Nancy Abbey is watching I Love Lucy, the title insignia is the famous heart-on-velvet, which was used only when the show was in syndication. The original opening sequence featured advertisements for a cigarette company.
The place setting Nancy Abbey uses for her etiquette class was not manufactured
prior to or during the 1950s. Although the china ("Prince Regent" by Royal Worcester) is inspired by an 1811 pattern privately commissioned by George IV as Prince Regent, it was not produced for public sale until the 1990s.
When President Carr is dictating the invitation for Katherine's return to Wellesley, her secretary is writing in shorthand that makes absolutely no sense. The only correct word is the first, which reads "Dear".
When Betty is typing her editorial against the school nurse, she narrates it as: "... has been willingly distributing..." but when we see what is being typed, she types "disb" as the start of "distributing."
When Katherine is walking along the outdoor corridor with the tile floor and columns before Bill gives her the belated Christmas present, the tile floor clearly has water puddles along it. When the camera moves to the close-up view and Bill gives the gift to Catherine, the tile floor is completely dry.
At the Adam's Rib party, Giselle is sitting in the window, with her hair parted in the middle and her forehead visible. In the next shot, when she moves into the room, her hair is parted on one side and sweeping across her forehead.
When Katherine visits Joan's house to show her law school brochures, there are palm plants in the front of the house. These plants would not survive in the climate of Massachusetts where the film is set.
During the convocation assembly at the beginning of the film, President Carr is wearing a gown and tassel that show she has a doctoral degree, but the cap she is wearing would indicate only a masters or bachelors degree.
With the exception of Christmas break, all the bar scenes are similar. Bill is wearing the same sweater, and Katherine's hair is always half-up, her earrings are always the same (as well as in the Christmas Break scene), and her outfit is the same by adding either a coat or a vest. These are all supposed to be happening at different times but are all very similar.
The goof items below may give away important plot points.
In the graduation scene, when Betty is asking Katherine Watson for the address, she is seen running out of the building, hair disheveled and no hat, but when her mother approaches her, she is wearing a purple hat like all the other girls and her hair is neat.