In the classroom scene where Harry A Kagan is talking, his necktie alternates between being tucked into the belt and in front of the belt.
When GO President Kagan is talking to Miss Barrett, his tie keeps changing lengths. In the close-ups it is short, just above his belt. In the long shots is appears to be tucked into his belt.
During opening scenes of kids returning to school, the voice of Miss Finch (Jean Stapleton) blares from public address system (urging students to report to different rooms, ignore real time bells, etc.), yet when Sylvia walks into office where Miss Finch is working, she has no access to a microphone or other broadcast equipment that would enable her voice to be heard throughout entire school.
As Miss Barrett exits the nurse's office, the nurse is wearing glasses. On the next cut, when the nurse says, "I give them tea. At least that's something", her glasses are gone.
During the opening montage establishing the first day of school in September in a New York high school, several shots were obviously filmed in dead of winter with extras in heavy coats, gray skies, etc. contrasting wildly with scenes of sunny skies and lightweight costumes of main characters.