Revealing mistake: When Brom (disguised as the horseman) throws the jack-o-lantern at Ichabod, there is a shot from Ichabod's perspective showing the jack-o-lantern flying toward him. It jiggles from side to side, revealing it was travelling on a wire.
Revealing mistake: When the headless horseman's head is being dropped into his grave it bounces on the dirt like rubber.
Continuity mistake: After the Hessian, carrying Lady Van Tassel on his horse, jumps back into the tree, her hand is prominently displayed sticking out of the roots. Ichabod faints and it cuts to a wide shot of the entire tree. You can see where the Horseman jumped into the tree but Lady Van Tassel's hand is not there.
Continuity mistake: When Katrina faints after having seen his father being killed by the Headless Horseman, Ichabod notices a pink chalk fallen from her hand changing position in another shot from an overhead shot.
Factual error: At the very end of the movie, Ichabod addresses to Young Masbath saying the final line "You'll son find your bearings young Masbath. The Bronx is up, the Battery is down and home is this way." However the Bronx was instituted only in 1898, a century later.
Suggested correction: 1. The Bronx was established in 1639, along the Bronx river by Dutch settlers, they started using the name Bronx. It doesn't have to be part of New York City for Ichabod to mention the location of the Bronx. There was already 2 bridges to it from Manhattan island even. 2. He could be simply referring to the Bronx river.
