When someone tells Jeremiah to tuck in his shirt he does, but it varies inconsistently between untucked and tucked-in in subsequent shots.
When Portia falls asleep in her office and is awakened by her boss knocking on the door (interrupting her dream about Jeremiah), she awakens with tousled hair and a "denied" stamp imprinted on her cheek. Her mascara is still in place, but when she opens the door to talk to her boss, the mascara on her right eye is running. Then, in the next shot (right after she closes the door) her mascara is not running or smudged and is intact again.
When Mark is reading the book of poetry in bed the book is open at different places in every shot.
When Susannah is outside Portia's car at the beginning of the movie, Susannah's necklace jumps in and out of her bib overalls between shots.
Twice Portia mispronounces her bonsai tree as a "banzai tree."
Defending the fourth-generation legacy, Brandt says "he's just one of those kids that doesn't test well." It should be "don't", since not testing well defines "those kids", not the single one. Not an error. If you omit the prepositional phrase "of those kids", it correctly reads "He's just one that doesn't test well." "Doesn't" refers to the "one" not "of those kids"
When Portia visits The New Quest school for the first time, a student asks, "Why should I apply to an elitist institution with a history of anti-black, anti-gay and anti-female oppression?" Here, the use of anti is not required, in the sense that one could refer to black/gay/female oppression and be understood, but it is not wrong, since anti- means against and it is oppression against those groups.
The Holstein cows are very skinny. No farmer would milk cows that skinny.
The characters drive back and forth multiple times between Princeton and some unnamed place in New Hampshire. Under optimal circumstances, that's about 300 miles and about 5 hours of driving. And that assumes no bathroom/food stops and no delays on the Hudson River crossing or, on the shortest route, the Cross-Bronx Expressway. And yet in the story it's treated like New Hampshire is one county over from Princeton., and the time and distance are simply not mentioned.