The sisters whisper "aegrota amore" which basically means "love sickness".
While waiting in the car Rowena asked Sam about music he tells her that "Dean may have a tape of Led Zeppelin's Moby Dick with an 8 minute drum solo." Actually, the live version has a 17 minute drum solo by John Bonham which is a record for the longest drum solo.
Elise Gatien, who plays the witch Jenny Plum, played Kristen on season six episode Live Free or Twi-hard (2010).
When Rowena is speaking in Gaelic, she uses the word 'sláinte' which translates to 'health'.