Lake Tay, or Tay Lake, is owned by the Guinness family and is not accessible to the public.
When Maddie (Lindsay Lohan) meets the mysterious lady at the magic stone, she mentions earthquakes and lightning. This happened in Lucky Girl (2006) and Freaky friday - Dans la peau de ma mère (2003), two prior films starring Lohan.
Killruddery House was the film location of the "Kennedy House" in the film, the location of many of the garden scenes including the lily pond and apple orchard, and the orangery was the location of the wedding scene.