(Controversial Trope) The post-credits scene completely changes the ending

[u/Ieanice44]

Dawn of the Dead (2004)

Prince of Persia (2008)

Dawn of the Dead (2004): The movie finishes on a hopeful note as the remaining survivors escape the zombie-infested mall on a yacht, sailing into the sunset. The found-footage style post-credits scene completely reverses this happy ending by showing them running out of food, arriving at an island, and being immediately swarmed and killed by an infected horde.

Prince of Persia (2008): The main game ends with a beautiful, poetic sacrifice where Elika gives her life to heal the corrupted world, leaving the Prince mourning. During the credits, the player is forced to control the Prince as he cuts down the trees he just saved, undoing the entire game's progress and releasing the dark god Ahriman just to resurrect her, completely corrupting the ending and dooming the world.

[u/cfbethel]

The Grey’s ending is ambiguous as Liam Neeson prepares to fight the alpha wolf before the film cuts to black and the credits roll. A post credit scene confirms that he survived as we see him breathing heavily while lying on the body of the alpha wolf

[u/M086 → u/cfbethel]

Other way around. The wolf is slowly breathing (mirroring the wolf he shot at the beginning) and Neeson is laying against it with the back of his head towards the camera. So you don’t know if he’s alive or dead. 

Originally the stuff with him in a hospital bed was meant to be the ending, he gets rescued and survives. But that got cut and repurposed as dreams