Continuity mistake: In the scene where Skeeter is on the phone with the lady who is interested in the book, she has an ashtray with a lit cigarette in it. In the next shot it is gone and the cigarette is in her hand, the next time it shows her the ashtray is back in its original position.
Factual error: There's a scene where one of the maids is vacuuming the bear in the house. At this point in the movie, it is around 1962-1963. President Kennedy hasn't been assassinated yet. Then the camera moves to a shot of the vacuum cleaner. It is an Electrolux Olympia canister made in 1978. I know, because I have two of them.
Factual error: When Minny is explaining to Celia how to cook/fry chicken, she lists things one can do with Crisco, all while holding the can of Crisco. The label on the can of Crisco was light blue until 1988, when it was then changed to the medium blue which is shown in the scene.
Factual error: Just before it shows Ailbileen using her newly built outside bathroom, there is a overview shot of Elizabeth's house. The house has architectural (3 dimensional) shingles installed but according to Nachi.org, these shingles were not introduced to market until the 1970's.