In the beginning, when the 3 brothers get attacked, they all get attacked while hiding near the same material they did in the story.
When talking to the surviving brother at the beginning, Dean introduces himself and Sam as "Detective Plant and Detective Page." If you look closely at Dean's ID, it says Detective Robert Plant. Robert Plant is the lead singer and Jimmy Page is the lead guitarist for the band Led Zeppelin.
Munchausen's Syndrome by Proxy is a psychiatric disorder wherein a person feigns, exaggerates, or induces illness in another, usually a parent to a child, to gain attention or some other benefit.
This episode centers around fairy tales coming to life, specifically Grimm fairy tales. However, the version of "Cinderella" referenced in the story (pumpkin, mice, Cinderella imprisoned) comes from the French version by Perrault. Grimm's version contained none of those elements.
When they first spot the pumpkin on the stairs before going into the house, Dean says, "yeah, it's close to Halloween". This episode actually aired the day after Halloween.