The entire film was shot using real locations. No sets were used.
David Krumholtz, who plays Michael in the film, wrote a piece for Vulture explaining why he thought the movie worked so well. He stated the entire cast became fast friends. "Joseph Gordon-Levitt turned me on to Phish, and I turned him on to Wu-Tang Clan," the actor wrote. "Gabrielle Union had us in stitches, Julia Stiles brought her own brand of SoHo-bred artistic intellectualism (at only 17, mind you), Larisa Oleynik's laughter filled the room, and we marveled at the tonedness of Andrew Keegan's muscles (a great sport!)."
Filming began without Heath Ledger, and the cast worried how his presence would change the dynamic. "This was a concern that was remedied a few days later, when he arrived and we found yet another comrade in sensibility. The group, with Heath, only got stronger. Before I knew it, the cast was experiencing what I've since found to be all too rare: a unified chemistry throughout the ensemble, without a single bad apple in the bunch. We all agreed that we were having the best summer of our lives."
Filming began without Heath Ledger, and the cast worried how his presence would change the dynamic. "This was a concern that was remedied a few days later, when he arrived and we found yet another comrade in sensibility. The group, with Heath, only got stronger. Before I knew it, the cast was experiencing what I've since found to be all too rare: a unified chemistry throughout the ensemble, without a single bad apple in the bunch. We all agreed that we were having the best summer of our lives."