Continuity mistake: For the first part of the movie, when they are meeting Esther and taking her home, the Lexus has tinted back windows. However, when the Lexus is rolling down the hill and thereafter, the back windows are clear.
Continuity mistake: When they meet Esther in the orphanage the painting keeps changing - one second there's another lion there and the next she begins to paint it.
Answer: The scene when Esther takes 4 bullets out of the gun and asks Max if she wants to play shows that the gun has a 5 bullet capacity. Esther fired 1 bullet at Kate's shoulder, 1 at a glass when Kate was on top of the glass roof and 3 other bullets at Max. At the end of the movie Max fires an extra bullet.