But after the first press screenings, producers responded exactly the way that Pitt feared: They went into panic mode and tried to figure out how to reshoot the ending without the Paltrow jack-in-the-box. The alternative ending -- the one they seriously almost went with -- was that Doe decapitates Mills' dog instead.
New Line Cinema
"You always wanted him to learn to play dead..."
Sure, John Wick proves that could have worked, maybe, after some extensive reshooting with additional scenes to highlight how much Mills really, really, f*****g loved his dog (do you remember him even having a dog in that movie?) but in the end Pitt convinced them to go with the original vision, and a classic was made. Albeit one that nets you some funny looks if you list it as "your favorite movie."