In the scene after Cynthia's funeral, when the girls are at the restaurant table, Brenda asks Elise about her surgery. When Brenda says "...the full enchilada", it's dubbed from "...the full Ivana" (as seen in the trailer), referencing Ivana Trump.
After the funeral, when the waiter brings the ladies drinks, he sets down a vodka during "just fine, couldn't be better" (Brenda's drink is already on the table). In the next shot, he finishes placing Brenda's drink, then the vodka, then reaches for Annie's. The next shot shows that Annie magically has a drink and the waiter is gone.
When the wives drop down on the window-washing scaffold, they pass more floors than there are in the building. Even after a free fall, a camera shot from below shows them to be still near the top of the building.
When Lisey, Bren and Annie are discussing Cynthia's death and the breakup of their marriages (before toasting the star of the First Wives Club), the letter in Annie's hand appears and disappears between shots.
When Duarto Feliz goes to Morty and Shelly's apartment, they make a big deal out of hiding an offensive chair by covering it with Duarto's long coat. At the end of the scene, there are several shots with him suddenly wearing it again.
In the scene where Brenda dumps the bottle of vodka and reveals all the bottles in Elise's trash can, the amount of liquid in Elise's glass changes--especially notable after she spins around quickly and the liquid goes flying, and then in the next shot, the glass is almost half-full again.