Early in Season 6 they had a nuclear bomb going off in Los Angeles and killing at least 12,000 people ... only to be forgotten a few episodes later. That is, a few hours later. In the world of 24, America gets over an attack four times the size of 9/11 before the emergency response even gets fully under way. Did the writers really plan it that way?
To quote writer David Fury, they were just "winging it." He says that worked out fine because they got good ratings doing it: "In the early seasons of 24, [the writers tried] to map out stories and arc out stories [beforehand] a little bit more than they did, say, in seasons four and five, and four and five turned out to be two of most successful seasons."
Making up plots as you go along tends to happen more in shows that unexpectedly become hits -as if the writers were pretty sure they wouldn't have to write too many episodes. There are more examples in this surprisingly SFW article at Cracked. Link -via The Daily What