Quick recap of the end of the film, we see Cable (Josh Brolinuses) use his time travel device to save Wade Wilson/Deadpool (Ryan Reynolds) from dying. There was only enough charge in the device for it to be used one last time, so Cable ends up locked in the past instead of in the future with his family.
After the end credits roll, Negasonic Teenage Warhead (Brianna Hildebrand) and her girlfriend Yukio (Shioli Kutsuna) working on the time travel device to try and make it work again. And they succeed!
Wade is given the time travel device and his first stop is the day his girlfriend Vanessa (Morena Baccarin) was murdered. He uses his cream cheese spreader to kill the would-be murderer.
Wade then goes back to the day that X-Force member Peter (Rob Delaney), the one who has no powers, dies and saves him from his death. He doesn’t save any of the other X-Force members who die though!
Wade then travels back to the 2009 movie X-Men Origins: Wolverine, when Ryan Reynolds made his first appearance as Wade Wilson/Deadpool. He is seen as a shirtless and mouthless man and the current Wade kills him off!
The final stop on the time travel tour is to the real Ryan Reynolds‘ home in 2010 while he is reading the script for the Marvel movie Green Lantern. Wade shoots Ryan in the head to prevent Green Lantern from existing! So there you go!
Here's also a visual recap explained, watch below: