Writer-producer-director Jack Bennett was given free reign by Anthrax to create what he wanted with only two stipulations; the band would not appear performing the song and someone had to get "blood eagle'd" onscreen.
The severed head being impaled on the spike in the torture chamber belongs to Greg Nicotero. It is the same head used in Inglourious Basterds (2009) when Hugo Stiglitz forces his hand into the mouth of the until-recently sleeping Nazi (played by Nicotero). The character impaling the head on the spike is played by Theodus Crane, who played "Big Tiny" on The Walking Dead (2010), which is executive produced by Nicotero and features effects by KNB EFX Group, the very creators of the severed Nicotero head from Inglourious Basterds (2009).
Upon hearing the description of his role, Cody Goodfellow quipped that he was playing "The Gorekeeper," which the filmmakers instantly adopted as his character's name.
The character played by long-time Home Movies (1999) fan C.K. Kimball is tortured to death by the character played by Brendon Small. This was arranged as a birthday present to Kimball from Jack Bennett.