The Making of Deadpool & Wolverine, it was revealed that there was an initial idea to show that Deadpool ( Ryan Reynolds) had been in the background of the MCU the entire time, with all of his appearances being left on the cutting room floor.

In the commentary, director Shawn Levy revealed how the ending for the film was already in the can when he decided to respond to a note by actress and Ryan Reynold's wife, Blake Lively and subsequently ended up reshooting for thirty-six hours.

Ryan Reynolds and Shawn Levy revealed on the “Deadpool & Wolverine” director’s commentary (via Games Radar) that the film’s ending changed thanks to a note from Blake Lively and less than two days of reshoots.

Marvel fans have Blake Lively to thank for Deadpool & Wolverine's killer ending. Ryan Reynolds and Shawn Levy revealed on the Deadpool & Wolverine director’s commentary that Lively's reaction to the movie caused them to reshoot certain scenes.