Corrected entry: There's supposedly several police officers observing Joker from outside the interrogation room through a two-way mirror, but none of them notice Joker taking Stephens (his guard) hostage until he escapes the room.
EK8829
1st Aug 2017
Correction: There are no other cops present, they have all gone to rescue Rachel and Dent. Only Stephens is there.
lionhead