We all know about deleted and alternate scenes that don't make the final cut for whatever reason. Most of the time it's decided they don't fit after they're already completed, but sometimes directors won't even bother filming scenes that have been scripted, usually because the film runs over budget and there's no cash left to shoot it, or it's decided that it simply isn't needed.
The problem with leaving it to directors, though, is that they're often wrong and in some cases, the audience actually NEEDS those scenes. After all, they explain plot holes or other curiosities that leave you scratching your head. Sure, the films function without them, but they'd be that little bit more water-tight with these inclusions.
Some, on the other hand, are just barmy fun, but nevertheless such a vital part of the original script that it's dumbfounding they weren't actually filmed.
10. Where Were The Police? - Batman
One of the most widely-criticised aspects of Tim Burton's Batman is that while the Joker has his chaotic parade in Gotham City, the police seem to do absolutely nothing. Well, the original script explains it perfectly; due to it being Gotham's 200th anniversary, a monument was to be unveiled in its honour on an island set away from the city, which had most of the city's police diverted to it because the Governor was on hand for the ribbon-cutting.
The statue is unveiled, but it has been vandalised, sporting the Joker's signature grin instead, just as the island descends into madness. Back in Gotham, the script notes that though there are police officers around, they are completely outnumbered by both the Joker's men and crazed citizens driven insane by material greed (alright, that last bit admittedly sounds a bit out there).
Had this ambitious scene been included, it would have made the parade seem not quite so awkward.