Visible crew/equipment: When Dani hands the spider back to Miles after he uses it to scare Flora, just after she says "Including me" and the spider moves from Dani's hand to Miles' hand, a red tape marker can be seen on the ground right under Victoria Pedretti's left foot. (00:34:09)
Factual error: The British schoolroom has a UK flag at the front. American schools might do that; UK schools don't. There's even a little one on the teacher's desk.
Trivia: The character of Dani Clayton is named after Jack Clayton, who directed "The Innocents." "The Innocents" is the film adaptation of the stage version of Henry James' "The Turn of the Screw." (Source: ScreenRant).