Dennis Hopper's landmark counterculture film Easy Rider gave Jack Nicholson his breakout role in 1969 — but it also led to Rip Torn suing the director!
Benedict Cumberbatch will soon be seen as multiple versions of the Sorcerer Supreme in the Multiverse of Madness, but Marvel almost missed out on casting him.
Guillermo del Toro ensure that the kaiju of Pacific Rim adhered to a specific design standard inspired by classic monster movies with rubber monster suits.
Bill & Ted's Bogus Journey almost had a completely different premise, which was instead used to launch the animated series based on the film franchise.
If there's a parallel universe where there's a Nicolas Cage in The Matrix and Lord of the Rings but not a Nicolas Cage in Pig or Mandy, we don't want it.