When Geoffrey leaves Noblet's classroom with the sign up sheet and mug, he is seen next in the hallway with only the sign up sheet for the science fair that he posts on the bulletin board.
Mr. Noblet and Mr. Jellineck already know and are in a relationship with each other, even though they are seen meeting and hooking up for the first time in the beginning of the series which this film is a prequel to.
The exterior of Flatpoint High looks completely different in the movie, compared to in the series which takes place immediately after.