The wall calendars in the newspaper's city room are for visibly different months. One begins on a Friday and has 31 days. Two begin on Sundays and have 30 days. Others appear to start on days other than Friday or Sunday. The kicker is the whole-year poster in Parker's office, which is for 1958.
The newspaper page John holds at breakfast is visibly different in the close-up shot compared to the before and after long shots.
Sunday night after the Champlain party, a radio announcer says the World Series is a week away. From 1960-62, the World Series began mid-week (Tuesday through Thursday), not Sunday.
Bob Hope is a theatre critic who having just seen a play returns to the newspaper office to write his review but the clock on the wall shows 5.30. . Being an opening night the play wouldn't have finished until at least 9.30.
As the kitchen scene with Angela, Parker and John is ending there is a shot that has the stove top grill visible. There is a small but evident amount of smoke rising from it. Possibly a crew member's or Bob Hope's cigarette dropped in the grill between shots.
While Angela works on her script outside John's school, the car she sits in has no rear-view mirror.
When Angie flies out for the first out-of-town preview of her play, it is late November or early December 1962, but both magazine issues John buys at the airport were published in April 1962 (cover dates in May 1962).