Theresa is supposed to be a first-grade teacher, but all her students look to be way older. The youngest seem to be 9 or 10 while the oldest could be 12, 13 or even older.
In the book, Theresa's sister Katherine goes to Puerto Rico to procure an abortion during a scene that takes place in the mid-1960s. In the movie, the timeline is changed so that this scene is set in 1975, two years after abortion was legalized by the Roe v. Wade ruling, making the trip to Puerto Rico unnecessary.
Just after James comes to Theresa's apartment to cook her dinner, a thin boom mic can be clearly seen in the upper right part of the screen, right in front of her "Punctuation Pointers" sign for school.