These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Adaptational Villainy: In the original story, Brom doesn't physically attack Ichabod, due to his rough sense of honor and fair play. He so thoroughly outclasses Ichabod physically that he might as well have two other guys there to hold him down as fight one on one, and limits himself to trying to hound him away from Katrina with practical jokes. In this version, however, he clearly was about to beat the snot out of him, and Ichabod only escaped due to Brom suffering a Wile E. Coyote-level bout of bad luck.
Also Katrina and Brom. Is she honestly flattered by Ichabod, or is she just playing with him, perhaps using him to make her other suitors jealous? And is Brom just a bully, or is he honestly in love and wants to protect her from a gold digger?
Hell Is That Noise: When Ichabod rides in Sleepy Hollow's forest you can hear the cricket chirping "Ichabod, turn back", an owls hoots "Go, go", a toad croaks "Headless Horseman", the wind blows the reeds and creates a sound like ghastly moaning and a crow caws "Here he comes" and "Beware, beware..."
One student also draws a caricature of Ichabod Crane - and you can see him about to smack the student with a stick (only the sight of the student's overflowing lunch basket stops him). To a viewer who was born after the 1970s, this would seem surprising - though this was standard behaviour for teachers at the time. (Even when it was animated!)