The film was originally to release on November 25 but was pushed back to December 4 to coincide with the Krampusnacht, a traditional Austrian festival held on December 5 that celebrates the Krampus coming to punish naughty children.
Michael Dougherty describes the Krampus in this film as Santa Claus's shadow: "He's not the unstoppable monster that kicks down your door and rampages and grabs you. There's something darkly playful about him. He's having a good time doing what he does, and he enjoys the cat-and-mouse aspect of it."
Krampus is a huge part of Austrian and German folklore. In Austria and southern Germany, they have "Krampus Runs" where grown-up men dress up as Krampuses and parade through the city streets and scare children.
Max's mom alludes to "the noodle incident" that estranged the family from a neighboring one. The noodle incident was often referred to but never explained in the Calvin & Hobbes cartoon strip, and Krampus also leaves it unexplained.
Michael Dougherty described the film as a darker version of a Christmas family film: "Christmas movies exist in their own little snow globe, where a clashing family, no matter how sick of each other, always manages to overcome their differences and live happily ever after. But what if the family's issues escalated, and then they sort of allow Krampus to seep into their reality?"
Composer Douglas Pipes described his music as a "collection of twisted Christmas carols, with pagan thrown in." He incorporated the sounds of chains, bells, bones and animal skin drums into the score, and had choirs chant and whisper in different tongues.
Understandably, with the controversy that surrounded other Christmas horror movies like Silent Night, Deadly Night (1984) and Black Christmas (1974), Krampus (2015) was a hard story to sell. It wasn't until Legendary Pictures agreed to a PG-13 rating that Universal green lit the movie.
In Max's room you can spot toys of Gypsie Danger and Leatherback from another Legendary Pictures film, Pacific Rim (2013). There are also posters from the show Rick and Morty (2013) and Robot Chicken (2005).
Just as the camera pans out from the A Christmas Carol movie on the kitchen television, there are many different Austrian desserts completely filling the counter and middle table, from Vanillekipferl, Linzer cookies and Christmas stollen bread on the counter. This helps establish the family's rich Austrian heritage to shadow what is to come.
In the movie, Max shares some candy from his "Halloween Stash" to comfort his cousins. Inside you can see a lollipop identical to the one used as a weapon by the demonic child Sam from Michael Dougherty's movie Trick 'r Treat.
In a cut scene, the fathers hear a blizzard warning for the Central Ohio area that covers "Franklin County, Delaware County, Ramona Falls, and Warren Valley." While Franklin and Delaware Counties are real (and place the film somewhere in or near the greater Columbus metro), Ramona Falls is really in Oregon, not Ohio. Warren Valley is the fictional town where Michael Dougherty's Trick 'r Treat took place.
At the beginning of the film, the TV in the kitchen is showing a news broadcast with the scroll saying, "Season's Greetings." Season's Greetings was a 1996 animated short film directed by Michael Dougherty that introduced Sam, the demonic Halloween spirit from Dougherty's cult classic Trick 'r Treat (2007).
Max's mother had the Santa family pictures taken, made and framed all that same night at Mucho Mart where Max's store play was on the Friday before Christmas which would have been the following Monday. In the pictures they are all wearing the same clothes they entered their house that night as can be seen when she hangs the newest framed picture on the wall after getting home.
Many of Krampus' minions are also real Christmas/winter folk figures in European cultures, such as the Yule Goat (Scandanavia). The creatures with Icelandic names (Stekkjarstaur, etc.) are named after the Icelandic Yule Lads who are said to visit homes each of the twelve nights before Christmas.
The trivia items below may give away important plot points.
Krampus's true face is hidden underneath a Santa Claus-like mask and is never fully revealed to the audience as a choice by the film makers to allow viewers to make their own conclusions on his actual appearance. His eyes and mouth are the only visible traces that can be seen through parts of the mask
According to Michael Dougherty, this is a Christmas film that is both scary and sentimental: "A Christmas Carol" and It's a Wonderful Life (1946) are nightmares that show you these broken characters who experience a darker side of divine intervention. They need to be scared straight."
The movie's ambiguous ending has spawned two fan theories: 1.) That the Engels and their family are trapped in the snow globe, condemned to repeat Christmas morning for eternity in a twisted version of Hell or 2.) They were given a second chance, and the snow globe is Krampus' means of watching over them. Although writer/director Michael Dougherty has refused to confirm which theory is true, the tie-in comic book, Shadow of Saint Nicholas, confirms that the happy ending is the true one. The comic has murdered characters resurrected without any hint of a twist, showing that Krampus is willing to give people a second chance as long as they prove they've learned their lesson. Unlike his grandmother, Max was brave enough to confront Krampus and prove he'd learned his lesson, which was why Max had his family returned and the grandmother's didn't.
The evil toys that attacked the family included an angel ornament, a teddy bear, a Jack-in-a box and a robot, similar to the evil toys in the movie Demonic Toys (1992) only instead of an evil angel ornament, it was an evil baby doll.
We see the evil nutcracker only twice and both times extremely quick. The first time is in the bag Krampus opens infront of Omi. The second time is at the very end in the upper right of the screen when we get a last glimpse of Krampus' minions.
Max's "noodle incident" which is an offhand remark from his mom is a reference to the comic strip "Calvin and Hobbes" where Calivin's "noodle incident" is mentioned multiple times without going in depth to what happened much like in Krampus only it is mentioned once