So let me see if i got this right (correct me if I'm wrong). I shouldn't need to spoiler tag since the movie's a thousand years old, but spoilers:



Marty McFly grew up in a dysfunctional family with loser parents and loser kids. He gets invited to a post midnight extravaganza by his eccentric scientician friend who gets killed while Marty accidentally travels to 1955, changes history, and goes back to a 1985 where he has successful parents and siblings. He goes back to see a scene which seems like the opening scene but it's really different. At this point I'm going to try to explain the plot of the movie, since Marty modified it:

Marty McFly grew up with successful parents and siblings and befriended an eccentric scientist who invited him to a post midnight extravaganza. The entire time the eccentric scientist knew who Marty was but kept it a secret, including the bullet proof vest he was wearing that morning. Doc Brown gets 'gunned down' and Marty McFly from the successful family goes back to 1955, presumably mirroring the exact same space/time position of Marty McFly from the world that was destroyed by the time this paragraph started.

Wait - that world was destroy. So the entire movie could not have ever happened.

then who was phone?