The production couldn't afford a proper underwater housing for the camera, so all the drowning scenes in the pool were shot with the camera inside a partially-submerged fish tank.
All of the scenes on the NYC subway and subway platform were shot guerrilla style with a minimal crew, long lenses, and the camera inside a duffel bag with a hole cut out for the lens.
During the scene where Tanner shows Kevin pornographic pictures on his computer, a crew member gave Tanner a new batch of highly-explicit photos for every take, so that Kevin would be authentically surprised each time.
Cinematographer, Mark Pugh, built a one-of-a-kind camera rig for the production. Nick-named the "stegosaurus" it was a hybrid of a steadicam and a six foot jib which allowed for long, fluid shots with amazing vertical range. However, when hyper-focused on shooting, Mark would move the rig around with no regards to what was happening around him. The backside of the jib contained heavy counterweights and gyros and would sweep wildly around behind him. It reminded director Nate Taylor of a stegosaurus's spiked tail wrecking havoc, and thus the nick-name was coined.
During several transitions the film contains frames of what appear to be static. Each of these frames actually conceal an image foreshadowing events later in the film.