Trivia: When Deadpool autographs the cereal box he signs it Ryan Reynolds.
Trivia: The two rednecks sitting on the back of the pick up truck when Cable arrives are played by Alan Tudyk and Matt Damon, whose makeup took 4 hours to apply.
Trivia: At the start of the scene where Deadpool and Weasel are recruiting the X-Force, they are looking at photographs of the applicants. The first photo shown is of Ruth Bader Ginsburg, an Associate Justice of the Supreme Court. A closer look at the photo will show that her superhero name is Notorious R.B.G. (00:53:55)
Trivia: A promotional poster for the PG-13 version of this film (Once Upon a Deadpool) was released as a parody of a painting commissioned by the LDS church called "The Second Coming." This was reportedly done in response to the state of Utah - known for the LDS church having unconstitutional influence over its state laws - fining a theater that served alcohol for showing the first film, alleging that it violated state liquor laws by serving alcohol while showing nudity or simulated sex.
Continuity mistake: In the final fight, Deadpool says to Cable "did you feel that too?" and there's no-one behind them at all. Cable moves forwards to kill a guy on the ground, and a fraction of a second later, as Deadpool says "only best buddies execute paedophiles together" an orderly has appeared in the background, who gets shot.
Answer: His change of heart came from Deadpool's sacrifice. In the second timeline, Cable saves Deadpool, but Deadpool had no way of knowing. Firefist still has a change of heart because Deadpool was willing to sacrifice himself, even though he was ultimately saved by someone else.
Now, I can accept that in theory, except that Russell repeatedly saw Deadpool putting his ass on the line to rescue Russell. I mean, Russell knew from the very beginning that Deadpool could have killed him (but chose not to) and took some severe ass-beatings on Russell's behalf. Russell was really, really hard-boiled, and I'm not seeing that Deadpool almost getting killed as enough impetus to change Russell's heart. It seems (to me, anyway) it was Deadpool's actual death that changed Russell, such that a mere deflected bullet would not have the same effect.
Charles Austin Miller
Deadpool often mentioned "lazy writing" and Russell having such a change of heart might be an example of it.
Erik M.
Deadpool saving Russell in the film is what made Russell think that they were friends. When Deadpool tells Russell that they aren't friends, he remains hostile toward Deadpool, not believing him when he later admits to caring for Russell. At this point Russell is too far gone and will kill. However, it's only when Deadpool takes a bullet for Russell, fully intending to die in both timelines, that Russell sees that Deadpool really does care about him, and would have died to save him.