When Prudie confronts her flirting husband in the hotel room, his shirt is unbuttoned but closed as he puts his hands on his hips. In a split second, it flies open, exposing full uncovered chest.
The mystery of Bernadette's disappearing ring. At the end of the movie, Bernadette displays a whopping great big ring for all her book club friends to see and in seconds it seems to have disappeared. Now you see it, now you don't.
After the first meeting at Starbucks, Prudie is on the far right. When Grigg explains where he lives, Prudie is closer to the group and her face obscured. When Grigg leaves and it goes back to the group, Prudie is on the far right again.
When Dean is washing his truck the soap suds keep vanishing and re-appearing.
Dean is seen heading off to the NBA playoffs in early spring (March). In reality they begin in late April and continue through June.
In the opening titles montage, the $1 bill being rejected from the vending machine has a picture of someone other than George Washington.
At the first library fundraiser, one of the characters remarks about "all of Silicon Valley" having shown up. Silicon Valley is located in Santa Clara Valley, not Sacramento Valley.
Jocelyn says she looks for a book at bookstores on State Street; there is no State Street in Sacramento or its suburbs.
When Allegra is separating eggs for the flan, she puts the first couple of yolks in the bowl with the whites, defeating the purpose of separating them. She is then seen taking the yolks out with the egg shell as she does this. (The actors had a limited number of takes available and Maggie Grace was forced to do this so she would not waste a take.)