We know in the film that Control has been working behind the scenes long before the event takes place. The Chem department, for example, has somehow gotten Jules to bleach her hair, and the hair dye “works its way into the blood” as a way to slow her cognition, and make her conform more the Whore archetype. Additionally, they have been lacing Marty’s marijuana to keep him dazed & confused. (Though, key to the plot, they missed his secret stash.) There’s even an actor placed en route to the eponymous cabin who unsettles the victims with his aggression and direct violent insults to Jules, setting the stage for their suffering. Though these things occur “off stage” of the actual cabin (and the Chem team works off screen), they help tell the story about how deeply embedded Control is in the world, and set the stage for the surveillance interfaces on stage.
Marking the deaths: on screen & ritually
The goal of the scenario is the suffering and death of the victims, in the right order. To provide a visual marker on the monitoring screens, a transparent red overlay is placed over victims who are believed to have been killed.
The choice of red has a natural association with the violence, but red has a number of problems. Visually, it vibrates against blue (according to opponent process of color theory, the red and blue receptors in our retinas are in the same place and can’t perceive both at the same time). It’s also typically used to grab attention, which in this case is the exact wrong signal. Jules is no longer in the picture, and so specifically no attention is needed for her. Better would be to dim her section on the monitor, or remove her altogether, if marking progress is unimportant.
Hadley orders Thorazine
In addition to marking the deaths in the digital interfaces, the deaths must be marked ritually for the system to work. To this end, Sitterson and Hadley act as the human interface that transfers the information from the electronic systems to the Bronze-Age mechanical systems behind him. Though this could be accomplished mechanically, there are ritual words that must be spoken and an amulet that must be kissed by a supplicant.
Sitterson, the senior of the two, recites, “This we offer in humility and fear / For the blessed peace of your eternal slumber / As it ever was.”
After these ritual actions, Hadley raises a roll top wooden panel to reveal a simple switch. Pulling it down initiates a chain of mechanics that ultimately break a vial of blood into a funnel, which channels the blood into grooves carved into a sacrificial slab.
Sitterson and Hadley mark the first sacrifice
The roll top door acts as a physical barrier against accidental activation, and the mechanical switch requires a manageable, but deliberate, amount of force. Both of these features in the interface ensure that it is only done when intended, and the careful mechanical construction ensures that it is done right.