Originally posted by: boris
TV series are very different from movies, you know.

Not all of them boris. Babylon 5 and X-Files are two examples of tv shows that did have a 5 year grand plan. Others, like Buffy the Vampire Slayer, don't really have a "grand plan". In all cases, I don't think a tv show has ever gone back to change something they didn't like. They either make it work in future episodes or they just deal with it as a small plothole.

The only tv show I know of that may have changed an episode is the musical episode of Buffy. The original airing ran about 5-10 mins long. All subsequent airings were said to have been cut short, so if you want to see the full ep, you have to buy the DVD. I don't watch a lot of tv, but I've still never heard of a show that made a change to an episode based on the director not liking something after the fact. Once it's aired, the only real changes they make are cosmetic (someone blinking at the wrong time or something).