Kiefer Sutherland injured his leg while leaving his trailer. The writers had him pull a piece of wood from his leg after the plane crash so they could explain the limp. The limp disappears after this episode.
When Michelle tells Tony about a co-worker telling her that he saw Mason throwing up in the bathroom, she is referring to a deleted scene (originally scheduled to be the opening segment) that featured Mason doing just that.
About four minutes into the episode, a noise is heard on the plane that Jack Bauer is in. This sound effect is taken from the PC game Doom (1993).