Patzer

When Sophie finds the Irish book about the leprechaun in the cellar she informs the others that 'Tuatha Dé Danann' means leprechaun. The Tuatha Dé Danann in Irish mythology were actually a tribe of kings and queens with supernatural powers that were worshiped as deities.

Ireland does not have woodland as depicted in the film. This is clearly filmed in North America.

When the four are tied to the tree, the leprechaun chooses to pull the surgical steel bar from Jeni's tongue instead of pulling her other gold earring or her gold necklace. Since the leprechaun is after gold, this makes no sense except for the shock and gore.