While the pilot was filmed in 2004, the bulk of the 22-episode first season was shot throughout 2005 .
The decision to film in 2005 was a pivotal moment for Fox. The network had originally passed on the show in 2003, fearing that a serialized prison drama wouldn't sustain an audience. However, the success of "lost-style" serialized shows encouraged them to greenlight production. when was prison break season 1 filmed