Continuity mistake: The position of the dead (imposter) security guard's head over the barbell changes. When Gus says, "Jesus, he's dead", the security guard's neck is over the barbell rail, the top of his head is touching the floor, and his face is toward the front of the screen. When the camera goes to the opposite side of the dead guard, his head and neck are raised (and apparently no longer being supported by the barbell - or anything else). (00:28:28)