Fromslashfilm [excerpt], Twin Pines Mall (real filming location: Puente Hills Mall in Industry, California, in eastern Los Angeles County) was the location that Doc Emmett L. Brown revealed his new invention, the DeLorean time machine, to Marty McFly. Anyone who has seen the movie remembers that the Libyan terrorists show up and Marty escapes in the DeLorean, which sends him back to 1955 without any plutonium to get him back home. This is the inciting incident of the film.
During the experiment, Doc becomes nostalgic about how he invented time travel and remembered that the land where the Twin Pine Mall currently stands in 1985, use to be farm land owned by Old Man Peabody, a crazy man who was obsessed with breading pine trees. And yes, we see Old Man Peabody and his family after Marty gets sent back in time and crashes into his barn. When Marty escapes, he runs over one of a pair of pine trees on display in Peabody’s front yard.
The result is when McFly returns back to 1985 later on in the movie, the name of the mall has changed to “Lone Pine Mall”.
