Continuity mistake: When Joe Clark is having his talk with Sams on the edge of the roof of the school, Sams is on the right and Clark is on the left (when viewed from the ground). When they're done talking, Sams turns to his left and walks away - turning to his left would have made him fall off the roof after just a few steps.
Continuity mistake: When the superintendent and the lawyer come to tell Clark about the Mayor and Fire Chief's plan to catch him chaining the doors (about 1:15:00), Clark is wearing a white tie with red stripes. At first, when Clark is walking down the hall with them, his tie is about 1 1/2 inches above his belt buckle (just above the bottom button of his shirt). Then, when he walks into his outer office with the Hispanic students, his tie suddenly creeps down about 3/4 of an inch (it is now slightly BELOW the bottom button of his shirt, and less than an inch above his belt buckle). At 1:16:45, when he walks into his inner office to meet with his teachers and security guards, his tie stays in roughly the same place. Later that day, when he is confronted by the female vice-principal in the hallway (about 1:18:20), he is wearing the same tie, but it is now hanging just BELOW his belt buckle. Clark may have adjusted his tie between his meeting with the teachers and guards in his office, and encountering the vice-principal in the hall, but he could not have done so instantaneously when he walked into his outer office from the hallway. (01:15:00 - 01:18:20)
Continuity mistake: In the first assembly, Sams and his friend are on the stage behind the guys beatboxing. The next cut is the teachers asking Sams and his friend to go up to the stage.
Chosen answer: They are discussing some of the things that Mr. Clark has done that has "embarassed" the school. They are debating what to do about him. And by "posturing," they mean his insistance on wearing African dress and espousing his political beliefs.