The subway sequence was shot on the NYC's 4, 5 & 6 trains from the hours of 1-5 AM. It took four consecutive nights of shooting to complete the scene.
During the scene where the victim beats himself mercilessly in the face, despite "careful" choreography to avoid injury, Elias hit himself in the mouth by accident with the very real cast iron stove grates used for the scene. Upon feeling the impact of the grate against his lips and teeth, he blurted out a terse expletive and then promptly continued with the beating! This one-of-a-kind take was left in the final cut of the film.
After many failed attempts to create the massive explosion of vomit needed for this shot, Elias finally decided to just vomit for real. Six bowls of died green oatmeal, two bananas, and a little olive oil as a chaser made up the contents of his stomach. Despite feeling sick as a dog after this willful force-feeding, it took 30 minutes and two table spoons of Ipecac syrup to cause the final eruption. With the moment of truth just seconds away, the camera battery died, but cameraman Ryan swapped it with a fresh one just in time to capture the ensuing vomitous scene.