The castley terrace where the Blackthorn says "Let the hunt begin" is the south terrace of Casa Loma in midtown Toronto. This Gothic Revival mansion and its gardens have been in just about every program filmed in Toronto.
When Bo says "Have fun storming the castle," this is a quote from the Princess Bride.
Zoie Palmer (Dr. Lauren Lewis) and Vincent Walsh (Lachlan/The Ash) previously worked together on the TV show 'Instant Star'. They played Patsy Sewer and Liam Fenway respectively.