What is on Doc Browns video tape at the end of Back to the Future?

Question

At the start of Back to the Future, Marty uses Doc's video camera to record Doc saying among other things, that the experiment is at the "Twin Pines Mall"

Shortly after this Marty throws the camera in the Delorean, takes off and accidentally runs over one of those twin pines in 1955.

1955 Doc watches the tape, but conveniently talks very loudly at the point where 1985 Doc says the location on tape. You can't really hear him say the location.

Marty eventually brings the Delorean and video camera back to 1985 to the new "Lone Pine Mall". What is on the video tape now?

If you watched the tape would Doc say Twin Pines, or Lone Pine?

Answer 1

The tape that the original Marty brought with him to the past would still say Twin Pines Mall. He gets to the mall a little too late to warn Doc about the Libyan attack and watches the NEW Marty speed off and go to the past in the parking lot, taking with him a new tape with Doc saying that he's standing at the Lone Pine Mall.

The photograph that Marty brings with him gives us the insight we need to determine this. Although the people in the photo started to disappear as Marty's parents' relationship became more distant, everyone came back after George punched Biff and kissed Lorraine wearing the SAME clothes as before.

We know that George socking Biff greatly affected his confidence and success. We know the rest of the family follows suit because everyone is in a lot better shape, the house looks nicer, they're wearing super nice clothes (by 80's standards), etc. The items that Marty brought back from the original future stayed the same even after events that changed them in the new future had already taken place.

If we follow this logic, the NEW Marty that left from the Lone Pine Mall would have an updated picture of his siblings, as well as an updated version of the videotape in which Doc Brown says he's standing at the Lone Pine Mall.

Answer 2

Have to disagree with @Yankimer, the video tape would have said "Lone Pine". The point that their clothes did not change is a bit tenuous. It just means their taste in "casual" clothes which they were wearing when the photo was taken didn't change, even if Dave now wears a suit to work. This is similar to how they still live in the same house at the end of the movie instead of in a richer neighbourhood. It may seem unlikely but it's fine for "movie logic" as one of the Bobs calls it. (In fact, George & Lorraine should have completely different kids because if their amourous behaviour at the end is anything to go by, they would surely have been having a lot more sex!)

On the other hand, any other changes seem to "catch up" with Marty and the new situation replaces the old as the causes of the changes happen - especially in the sequels when they see the changing newspaper headlines & photo of the gravestone - but even in the first movie the photo depicts his family disappearing when it looks likely that George and Lorraine will not get together. If the photo is changing as a result of them not getting together, then why would the video not change when Marty ran over one of the pines?

It appears the only thing that does not change is the time-travelers' own memories.

Answer 3

It's possible that the answer might be "both, or neither". In the movie version of BTTF3, once Marty had deflected Buford's bullet aimed at Doc, the name "Emmett Brown" disappeared from the gravestone in the photograph but the stone itself and the date remained, with a blank space where the name should be. But in the novelisation, the names "Emmett Brown" and "Clint Eastwood" were superimposed upon one another, like a double exposure. So in the case of Lone Pine/Twin Pines, there was always the possibility that Old Man Peabody could have replaced the damaged pine with a new sapling, until he sold the land and the shopping mall was built. Therefore, between Marty demolishing the pine and that moment, both names were possible. Using the same logic as the movie version of BTTF3, there would have been a moment of silence on the tape when Doc said the name; using the logic of the novelisation, both names would have been heard simultaneously.