We all suspected that George Lucas didn't really have his stories written in advance when it turned out that Luke Skywalker's love interest was (spoiler alert!) his sister. That kind of thing happens more often than you think in movies and TV. For example, you'd expect with a TV show like 24, the story of the entire season would be planned -after all, it's supposed to be 24 consecutive hours of action! But no...
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
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
There was a cheap magazine (I wish I could remember the title) which stated that Lucas already had the story planned out... and that Darth Vader was put into the suit after a fight with Obi-Wan Kenobi, in which Vader was stabbed with a lightsaber and fell into lava.
If the story arc wasn't planned out at least generally, then that is a wild coincidence.