Walter and Jesse shoved his character's corpse into a barrel to dispose of it with hydrofluoric acid. Following that scene, Jesse lifts the barrel with a forklift and it is lit in a way that the barrel can be seen through. This was accomplished by back-lighting the barrel and tying monofilament to the bottom of it, which staff members then moved and twisted outside of the view of the camera to create the lighting effect. Analysis A major theme of "Box Cutter" involves Walter's gradual change from an unwitting participant in a drug-dealing enterprise into a man more comfortable with a life of crime who embraces his darker side and becomes more proactively violent and dangerous. This development began during the latter episodes of the third season and would continue to be a major theme throughout the fourth season. The episode also introduced the ongoing theme of Jesse's moral decline and self guilt over his killing of Gale. Aaron Paul said of this, "Jesse's much more raw this season. He's very distant, and he's turned to just utter chaos and destruction to keep his mind busy. When he's left alone in his own thoughts, that's when things can get kind of dangerous and scary for Jesse." The scene when Walter pleads with Gus demonstrates the paternal sense of protectiveness Walter has developed for Jesse. During that scene, Walter tells Gus, "You kill me, you have nothing. You kill Jesse, you don't have me." Jesse is visibly moved by the statement, which Aaron Paul described as "the first moment that Jesse realizes that Walt's loyalty is to Jesse." "Box Cutter" also illustrated Skyler's growing involvement in Walter's illegal activities through the subplot in which she lies to a locksmith to break into Walter's house, going so far as to use her baby as a prop in her facade. After Skyler breaks into Walter's apartment, she finds the plastic eyeball of a teddy bear that has been part of the series since the second season. The eye has long been used as a symbol to identify Walter's gradual descent into a life of crime, and Skyler's discovery of it symbolizes her own similar descent. Cultural references During a scene when Gale's neighbor calls police to report his murder, a clock in Gale's apartment reads 10:13. This is a deliberate reference to the number 1013, which frequently appeared in The X-Files, where Vince