Revealing mistake: When Dredd throws Kay onto the table, Kay is supposedly handcuffed, but his hands spread apart way further than they should have.
Revealing mistake: When Dredd headbutts Kay, you can see that he actually misses. You can tell because he moves forward further than Kay's face would allow.
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