When the superintendent is discussing who to hire as the principal with the Mayor, the Mayor asks "What was last year's score?". The Superintendent answers "38%". Later, when Joe leaves the stage after expelling the bad students, there is a chart that shows that last year's score was 30%.
When Darnell flips Clark's desk, all of the contents fall to the floor with the exception of a couple of pens in a holder, and Clark's name plate, both of which land in his chair. After Darnell leaves, Clark then straightens the desk back up, and when he gets on the floor to pick up the other contents, the pens and name plate have disappeared without him touching them.
Maria's hair between shots when Clark is somewhat berating Mrs. Powers over the way she taught the school song to the "song birds".
The practice exam booklet reads "New Jersey Minimun Basic Skills Tests"...probably the last place the school board (or the film's producers) would want a spelling error.
The film portrays Joe Clark as becoming the principal of Eastside High School for its 1987-88 school year. In reality Clark became principal in 1982 and remained there until shortly after the film was released in 1989.
The film establishes that the state of New Jersey was threatening to take over Eastside High School from the city of Paterson if the school did not increase its test scores. In reality no such take over was looming, however, in the early 1990's Paterson's Public Schools would be designated an Abbot District. Abbot Districts are schools systems that the state take control of, providing capital and resources to them, so that students receive an education that is in line with New Jersey's state constitution.
After Mr Clark is done keeping the Fire Chief out, on his way back into the school he tells Mr Darnell its good to have him back. Mr Darnell says "You should have never fired me in the first place". He never fired him. He suspended him.
Since crack is a highly addictive substance, Thomas Sams wouldn't have been able to detox and quit cold turkey in such a short period of time.
Mr Clark stops Sams in the hallway when he's about to duck into the bathroom to look for his friends. He begins to question Sams how he's doing in class and asks when he gets his report card. The principal of a school, especially one as hard-nosed as Mr Clark would know when report cards are issued.
Correction: Mr. Clark probably does know, he is keeping his promise to Sams of being on his case and is making sure Sams knows the information.