2) Pretty Much Everything – The Amazing Spider-Man 2
So confident were Sony with The Amazing Spider-Man series that they’d planned further sequels and spinoffs before the second film was even finished. The sequel teased several storylines that were meant to be explored further down the road, but thanks to the film being a commercial and critical disappointment – and the character subsequently being rebooted in Captain America: Civil War – we’ll never know how things were meant to pan out.
Unresolved plotlines include what happened to Richard Parker, which the movie spends a lot of time setting up but doesn’t bother to pay it off. Furthermore, we still don’t know who the mysterious man in the hat was meant to be, Green Goblin ends the movie planning his revenge by assembling the Sinister Six and Felicity Jones was clearly meant to become Black Cat in the next movie.
Most importantly of all, though, is whether or not Aunt May become a successful nurse. Sadly, we’ll never have the answers.