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."

The Krampus's final design was distilled from various postcards and illustrations of the creature over the years.

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?"

The opening sequence was shot on location in a single day at a department store in New Zealand.

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.

The Christmas photos seen during the ending credits were gleaned from various cast and crew members.

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.

Oma (=Granny) Engel is the only person to refer to Krampus by name.

Michael Dougherty originally wanted to use the Universal Studios logo from the 1980's at the very start of the film.

The snow on the ground was made from material that's usually used for diapers.

Krista Stadler was cast at the last minute as Omi after three previous actresses bowed out from playing the role for various reasons.

95% of this movie was shot on a soundstage.

Lolo Owen (Stevie) is Stefania LaVie Owen (Beth)'s real life younger sister.

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.

Omi was deaf in the first draft of the script.

In Max's letter to Santa Claus, his full name is Max Engel. The name "Engel" is the German word for "angel". This hints at his family's Austrian heritage.

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.

Was dedicated In Loving Memory of director Michael Dougherty's mother Ramona Grace Dougherty.

Not screened in advance for critics.

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.

Italian theatrical release was originally set for December 3rd 2015, and trailers were even shown in theaters, before being canceled.

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.

The house Krampus is standing on in one movie poster is a different house seen inside the snowglobe held by Krampus on the other movie poster.

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.

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 film's version of Krampus hints that he is Father Christmas's dark side Omi Engel describes Krampus as Saint Nicholas's shadow Krampus operates in a similar manner to Santa, with minions and a sled and the bell Max receives has "Gruss Vom Krampus" engraved on the side, which means "Greetings from Krampus".

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.

When one of the adults fights the teddy bear-type toy, she throws it down from the attic and you can hear the WILHELM SCREAM.

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