In the record smashing scene, as the students exit the classroom, Santini(Jamie Farr) is shown walking down the hallway, but in the next shot he is still in the classroom,giving Mr.Edwards his glasses.
When the hoods break Josh's record collection, one of the kids starts playing a record and we hear music. During one part of the scene we see the phonograph arm playing the final groove of the record indicating that the record has finished playing, but we can still hear the music.
As Professor Kraal escorts Dadier through the suburban school, the sound of students singing the national anthem is heard in the distance, louder in each succeeding scene, missing no verses. Kraal and Dadier are eventually shown ending their tour in the school auditorium, where they've joined the students in singing the anthem's final verse. However, in order for the two men to be present during the assembly while the students were still singing the anthem, the students would have to have sung the anthem over and over again for the entire time it took for the two men to tour the school.
In the maternity hospital there is a sign reading "DOCTOR'S LOCKER ROOM" with the apostrophe after the R. This would mean that there is only one doctor. It should read "DOCTORS' LOCKER ROOM" where the apostrophe after the S indicates more than one doctor.
In the garage scene, when Miller starts fixing the car, he says "nobody gives a hoot", but his lips indicates he really says "nobody gives a damn". The replacement of the profanity is made humorous by the director, who chose to play the sound effect of a car horn when the word "hoot" is uttered.
The goof item below may give away important plot points.
In the climactic knife fight with Dadier and West, West slashes Dadier's hand with his knife. Ultimately Dadier grab's West's shoulders and shakes him violently, his right hand bleeding profusely on West's left shoulder. The next scene as West is being led off to the principal's his left shoulder appears clean.