Given how many decisions go into making a single movie and so many cooks in the kitchen, it's inevitable that some important decisions are going to be made on a day to day basis. Sometimes, right at the end of the day.
It happens in real life too, of course, but the key difference here is that our work mistakes or successes tend to not be remembered globally, whereas in the movie business they can have a universal knock on effect in defining a generation's favourite flicks.
No pressure then.
The next time you select one of your all time greats on Netflix or dust off an old DVD for a nostalgia fest, stop for a second and think about what could have been if your favourite character, scene or line was recast or cut, respectively.
On second thought, relax. I'll do it for you.
10. Bill Hader Embraces His Inner Droid (Star Wars Episode VII: The Force Awakens)
SNL alumni, Bill Hader, finally looks to be enjoying the widespread praise and acclaim he has long been overdue - his recent Emmy award being more than deserved.
Since his early appearances in Superbad and Knocked Up, he's genuinely very funny and has a remarkable charm about him. He's also had stellar voice over (Cloudy with a Chance of Meatballs and Inside Out) and dramatically comical (The Skeleton Twins and Barry) turns.
What you probably didn't realise is that he also voices one of the galaxy's cutest little droids, BB-8.
Listed as a 'vocal consultant' in the credits, he first tried doing a 'BB-8 voice' but they all agreed it sounded too human - it did mean that Hader was one of the first to see the film, though.
Feeling as though he'd blown his big Star Wars opportunity, Hader was shocked when JJ Abram's number popped up again. Billboards were already up for Star Wars Episode VII: The Force Awakens, which shows you how late in the day this exchange was.
For the second recording, Hader spent an hour making noises into a talkbox as Abrams fiddled on an effects app on his iPad.
Hader's work isn't heard in The Last Jedi but he managed to swindle a Star Wars credit from an hour's worth of beeping.