During the class change scene, the knob on the banister gets broken, but can be seen soon after as unbroken.
When Miss Gossage writes her name in the dust, the long shot shows shadows of the vase and a structural feature on the dusty surface, while the closer shot just has the shadow of the vase.
Near the beginning it is stated that there are two hundred and seventeen trunks and lunch boxes on the driveway. The following shot shows about forty or fifty trunks - considerably less than two hundred and seventeen.
The boys' and girls' fight on the playing field seems far from antagonistic: most of the cast appear to be suppressing laughter.