Continuity mistake: Mama has a smaller and fainter scar on her left cheek. It is missing when Kay brings her Anderson.
Continuity mistake: During the firefight with Dredd and the other 2 judges in the drug lab, Dredd runs out of ammo as he tries to cycle through available ammo types. The split-second view of his guns display says 00ap | 00in | 00he | 00fmj, then when he says high-ex the gun acknowledges the command, even though he is totally out of ammo according to the ammo counter. Next frame goes back to the gun's display but now magically he has 25ap | 25in | 25he | 50fmj with the "25he" being highlighted. (01:15:02)
Continuity mistake: The two backup judges have just arrived and are asking to be let into Peach Tree. Mama has a knife on the tech guy's stomach, coercing him to keep the blast door shut. In every shot from the behind, her left hand has a firm grip on the guy's shoulder. In shots from the front, the hand is absent. (00:55:00)
Answer: Kay wanted to punish her for what she did to him earlier. Ma-Ma wanted leverage against Dredd should he get past her Judges.
MasterOfAll