This episode is dedicated to Matt Riley. He was an extra and a stand in for Jared Padalecki. The cast has honored him and his struggle by urging people to understand mental illness, get help, and help those in crisis.
As Rowena is preparing a spell, she's cheerfully humming the folk song "Scotland, the Brave." She and Crowley/Fergus are originally from 17th-18th Century Scotland. The tune is actually dated early 20th century, but is considered one of Scotland's unofficial national anthems.
As Rowena is cutting Crowley's tie, she is humming "Loch Lomand". Later she hums "Scotland the Brave".
The title of this episode is a play on the popular YA novel series (and subsequent film adaptations) The Hunger Games.