When Dean and Annie are on the phone, Annie says she is in Bodega Bay and staying at the Crow's Nest Hotel. This is a reference to Alfred Hitchcock's film The Birds (1963), which takes place in Bodega Bay, where characters are attacked by crows and other birds.
When Dean and Sam walk back into the house, and Dean thinks he hears something, he says "Slimer?", a reference to the iconic ghost from Ghostbusters (1984).
Haunted house is the Tulk House (Rosemary) in Vancouver. It was also the Pierpont Inn in episode 2-11, Playthings (2007).
As revealed by the boys' discussion as they wait in the restaurant at the beginning of the episode, Annie is officially the only woman lucky enough to have "had a thing" (intimate contact) with BOTH Winchester brothers (and apparently Bobby as well).
Fourteenth episode to not feature the Impala. Thirteenth episode in a row to not feature it. Except in a small flashback scene that took place four years earlier in Repo Man (2012).