Sequels are a tricky business. Every time Hollywood hits it big with a movie that draws the crowds and piles up the box office receipts, you know that someone somewhere is discussing the possibility of them doing it all over again.
It's easy to be cynical about this, but for fans there's often a great deal of joy to be taken from this. If a movie gives us endearing characters, plenty of action and spectacle, and leaves the story just that bit open enough at the end, then why not do keep it going? More entertainment for us, more money for them: win-win.
The problem is, once any franchise is a few films in, there are invariably differences of opinion as to where they should go next. Sometimes they run short of ideas; sometimes they just have too many ideas to choose from. And sometimes, as we'll see, the ideas they come up with are just that bit too bananas.
Whatever happens, any ongoing movie series is going to have left a few sequel ideas abandoned along the way; and in some instances, hindsight tells us that the sequels which got left behind may very well have been a whole lot more satisfactory than the sequels which ended up getting made.