The Glade 4.0

...these scenes also destroy the galaxy that the games spent so much time developing. No matter what the player chooses, the mass relays detonate spectacularly, releasing massive shockwaves. In the world of the game these relays are the lynchpin of galactic travel and commerce, and their removal separates its the various worlds by voyages that take years, rather than moments. Demolishing the paths of commercial and cultural exchange that defined the galaxy, however, is a minor problem compared to what the game itself states will be the result of the exploding relays.

Although it has recently been demonstrated that mass relays can be destroyed, a ruptured relay liberates enough energy to ruin any terrestrial world in the relay's solar system.

—Mass Effect 3 Secondary Codex, "The Reaper War - Desperate Measures"

Did you choose to cure the genophage, or do what the Dalatrass asked? It doesn't matter. Tuchanka and Sur'Kesh were destroyed.

Did you save the Geth, or the Quarians? Who cares? The fleet is wrecked and Rannoch has been obliterated.

Did you take back Earth, as the game's ad campaign promised you would? Not in any meaningful way: the world you fought to save is gone.

Was your Shepard a paragon? Too bad, buddy; now she's the galaxy's worst war criminal.

The Extended Cut adds a scene with Shepard's squad being critically wounded by Harbinger during the push to beam, forcing Shepard to call in the Normandy to extract them before pushing on and also being injured. It also shows the mass relays as being heavily damaged by the Crucible's firing instead of being destroyed as per the original ending. Additional scenes and dialogue have been added to clarify events and resolve perceived plot holes. The flashbacks of characters after Shepard's decision have also been fixed so now the first will be that of Anderson, the second someone who died over the course of the game, and the third whoever was Shepard's love interest.

The three original ending choices have been modified to include a varying narration provided by Admiral Hackett (Destroy), a Reaper artificial intelligence modeled after Shepard (Control), or EDI (Synthesis) along with slides showing the impact the player's choices have had upon the galaxy, as well as the fate of surviving characters. If the player has a sufficiently high EMS score, the surviving crew of the Normandy is shown holding a memorial service for Shepard before repairing the damage from the crash and launching into space. If the player chose to destroy the Reapers and survived the Crucible's blast, a squadmate or love interest will refrain from putting their name up on the Normandy Memorial Wall and will instead smile hopefully.

The Extended Cut also provides a fourth ending, triggered by either refusing the Catalyst's choices, or attempting to kill it when the player resumes control of Shepard. Consequently, the Crucible is not fired and the war ends with the systematic destruction of all space-faring civilizations, and the continuation of the Reaper cycle. The scene then shifts to an unknown garden world in the future where one of Liara's beacons has been discovered. Dialogue in the post-credits scene reveals that the knowledge gained from the beacon ultimately led to the next cycle's victory over the Reapers.