I don’t know about un-necessary postscripts, but I can think of a movie that badly needed a postscript and didn’t have one: the 2003 film Ned Kelly, starring Heath Ledger and Orlando Bloom.
If you haven’t heard of the film, don’t be surprised- I’m told it went straight to video in most places outside Australia, NZ, and the UK, and with good reason (it wasn’t very good, for starters.)
Anyway, at the end of the film after Ned Kelly has wandered out of the Glenrowan Inn wearing his home-made armour and had the crap shot out of him by the police, the film fades out on a shot of the injured Ned Kelly in a railway carriage being taken back to Melbourne.
Now, if you didn’t know anything about Ned Kelly (and most people outside Australia don’t), then you might conclude that there could be a sequel in the offing.
Wrong.
Ned Kelly was taken back to Melbourne, tried, and then hanged on November 11th, 1880 at Melbourne Gaol, a little under five months after the siege at Glenrowan.
Of course, the film makes no mention of this at all- you’d have to either know your Australian Colonial History, or care enough to look it up on Wikipedia to find out that Mr. Kelly’s career as a human tank prototype ended rather unpleasantly in a Colonial Prison in Melbourne.
Still, one day someone will get it right, much like that “Proper” version of The War Of The Worlds I keep hoping for, the one with Jeff Wayne’s music, set in the 19th Century, with Dreadnoughts and British Imperial Soldiers, and Martian Fighting Machines, and a decent budget, and good actors…
Although the chances of anything like that coming from Hollywood are a million to one, they said…