Revealing mistake: This happens at the end of the movie. When No Good is tenderizing the meat with the brass knuckles, you can see that his hand doesn't come anywhere near the meat.
Continuity mistake: When Lonnie goes over to Rolanda's house to take Carver he grabs the baby and buckles him in the car. After he punches Rolanda's cousin and gets in the car to drive away you can plainly see the baby is no longer in the car.
Plot hole: At the party towards the end of the movie, the 3 babies are crawling around on the floor. There's no way not one person at the party saw them.