Continuity mistake: During dinner after the funeral Streep has a cigarette in her hand. The next shot her hands are together without a cigarette.
Factual error: Near the beginning of the movie, the Slowhand album is on the turntable and the song "Lay Down Sally" is playing. The needle is near the end of the record, even though the song is the third of five tracks. Near the end of the movie, Meryl Streep drops the needle much closer to the beginning of the record to play the same song again.
Other mistake: Barbara and Violet are talking in the car after returning from the funeral and all of the windows are closed, even though great effort was made to convey the fact that temperatures were in excess of 100°. They spend three to four minutes talking in the car and neither even breaks a sweat, when in reality, they could not have sat in a closed car in that kind of midday heat for more than 30 seconds or so without becoming incredibly uncomfortable.
Factual error: When Benedict Cumberbatch arrives by bus to Oklahoma City a digital sign shows the temperature at 104°. Yet as soon as he gets off the bus he puts on a woolen jacket. And Chris Cooper, who is waiting for him outdoors, wears a perfectly ironed and dry white shirt, which given the hellish heat ought to be soggy, rumpled, and sticking to his body.
Other mistake: When Ms Nicholson's boyfriend arrives in a bus, a digital clock is showing a temperature of 104°. Yet this man, as soon as he gets off the bus, puts on a woolen jacket over the shirt and tie he's wearing.