The address of the creepy house is 313 Mockingbird and the name of the asylum car outside is Radley, both are in reference to "To Kill a Mockingbird" by Harper Lee.
the little boy hanna and alison are babysitting in the flashback scene is writer/creator I. Marlene King's son
1313 Mockingbird Lane was the address of the Munsters.
In this episode, they paint Ali's nails black instead of the typical pink during the introduction while they are preparing her for her casket.
When Alison says to Emily : "Were you wishing you could taste her Cherry ChapStick ?" because Emily is watching Jenna dancing, she's making a reference to Katy Perry's song "I kissed a girl".