When Wednesday confronts Thing about being followed, Wednesday posits that her parents are spying on her. Thing spells the word "Worried" using American Sign Language finger spelling.
Jenna Ortega really played the cello accompaniment to Paint it Black.
The phone number Thing gives Tyler to call is (413)555-1938, the last four digits, 1938, are the year that The New Yorker first published Charles Addams's comic panel "The Addams Family".
The episode title, as well as Wednesday's name come from an old nursery rhyme. "Monday's child is fair of face/ Tuesday's child is full of grace/Wednesday's child is full of woe/ Thursday's child has far to go/Friday's child is loving and giving/ Saturday's child works hard for his living/And the child that is born on the Sabbath day/Is bonny and blithe, and good and gay.
The song playing while Wednesday exacts vengeance during the swimming-pool scene is Edith Piaf's "Non, Je Ne Regrette Rien," which translates to "No, I Regret Nothing."