The "Señor Skeletinos" found at the Halloween store are dressed as Mariachi.
The entrance of the Krustyland attraction is very similar to the real-life entrance of The Simpsons Ride at Universal Studios.
The Krustyland event "Halloween Horror Night" is a likely reference to Universal Studios' Halloween Horror Nights events which are done at Universal's theme parks in Orlando, Hollywood, Singapore, and at Osaka, Japan.
The house on the hill in the background at Krustyland is the house from Psycho.
The monster Cthulhu appears behind Lisa when Homer is trying to calm her.
The evil baby in the carriage is a reference to the 1974 film It's Alive.
The chestbuster creature from Alien attacks Lisa from the inside of a security guard. This is a reference to the franchise films Alien and Alien 3.
Ned asks Homer if they're they're heading up to the treehouse, to tell three horrifying tales? and Homer answers they're doing it next week, referencing to the following week episode "Treehouse of Horror XXVI". ("Treehouse of Horror series")
Reverend Lovejoy and Helen Lovejoy are dressed in the same costumes they wore when they disguised themselves at a casino for a card counting operation. ("Sky Police")
Agnes Skinner and Willie hook up again. ("My Fair Laddy")
According to Al Jean, this was a canon Halloween episode making it the first of its kind and aired in addition to "Treehouse of Horror XXVI" but aired in a different week.[1]
The production code TABF22 is on the Groupon for a zip line adventure.
This episode has yet to air in the UK however this might have been done due to its higher rating.
Maggie Roswell makes an uncredited appearance voicing Luann Van Houten in the Grownup Halloween song.
During the "Adult Halloween" musical number, Sideshow Mel is drawn too tall in some shots.
Professor Frink's glasses change throughout the "Adult Halloween" scene.
When Homer sits on the couch to calm Lisa down, he puts a popcorn bowl beside her, but when the three employees ring the doorbell, the bowl disappears and Homer places a puzzle box on its place.
The products at Apu's Official Halloween Headquarters change places between scenes.
After Lisa plugs in the decorations, when Homer cries for help, his mouth doesn't move.
Bernice costume switches from white to purple when Marge returns home.
When Homer and Lisa are running upstairs from the invaders, Tailee disappears from Lisa's hand and reappears when they are upstairs.
The same mistake occours when Lisa is climbing onto the roof: Tailee disappears when Homer is holding her and reappears when she gives it to Homer.