When Felicity catches Curtis on his way to the gym, he's wearing a jacket that reads "FAIR PLAY" on his right arm. This was the Logo/Endorsement of the superhero Mister. Terrific. (Further indication that Curtis will take up the Terrific mantle)
Matt Ryan's acting schedule initially looked like it would prevent him from appearing in this episode, in order to give him time for filming this episode they swapped production time for episode 4 'Beyond Redemption' and episode 5 'Haunted', filming episode 5 first gave Matt Ryan enough time to be in the entire episode.
The title is a subtle nod to the cancellation of the "Constantine" TV series, by being named after Warren Ellis' 1999 storyline "Haunted" from the comic books (Hellblazer #134-139), and the fact that Ellis left the book that year after DC Comics refused to publish his single-issue story "Shoot" for Hellblazer, about high school shootings, following the Columbine High School massacre (20 April, 1999). "Shoot" was finally published in 2010 in Vertigo Resurrected: Hellblazer - Shoot #1.