I don't see any problem, myself; in Back to the Future (I), when Marty comes back to the present, to find a successful family in place of the more unfortunate one that he had left behind, he had no memory of the new events which had brought the new situation about. (apparently in the Back to the Future universe, time travellers are not affected, immediately at least, by changes to the timeline.)

so what Marty remembered was the name of the ravine, from the original(?) version of history.

When he saw Doc Brown's tombstone, that was because history had been altered without him being aware of it; "Clayton Ravine" was probably called something else in that timeline (but not yet "Eastwood Ravine", because he had not yet gone back in time to cause that change.)

time travel is tricky like that...

on a related note, I recommend reading Orson Scott Card's "Pastwatch: The Redemption of Christopher Columbus"; it's quite excellent, and explains causality and timestreams in an interesting way...

Here is a possible explanation, Marty went back to save the Doc TWICE, we only saw the second. The first time he helped save Clara, but failed to save The Doc, he then returned to '55 or '85 and altered the timeline in some weird way we didn't see in order that the Marty who was in the movie would manage to save the Doc.

Another possibility is that the Doc had the tombstone put in (with the addition as a joke or romantic gesture) in order to make sure that Marty would still come back, as without it he would not, in which case the tombstone WOULD be there since he would have died...

I'm surprised no one has mentioned this MAJOR plot hole in Back to the Future II:

You can't visit yourself in the future.

Okay, so there is that pesky suspension of disbelief thing, right? I'd be willing to buy that argument except: The parameters for traveling into the future were already established in the original Back to the Future. Got your copy of the movie ready? When Dr. Brown first demonstrates the time machine for Marty (who is videotaping), he has his dog Einstein get into the car and sets the time circuits for one minute into the future. After the car hits 88 miles per hour, it vanishes - traveling into the future. Now for an entire minute, where is Einstein? That's right - he's gone! See, that's how traveling into the future would work, and how it is shown in the first movie.

Back to the Future II couldn't happen because when Marty and Dr. Brown go into the future, Marty would no longer have a family - he would have been missing since the day he time-traveled from.

This creates the largest plot hole of all for Back to the Future III, the movie that came before it couldn't have taken place at all.

Since adding this node, another node has been placed to dispute this theory. While it doesn't bear repeating, the mere intention to see yourself in the future does not give you that ability. Einstein's trip was instant to him because he was in a device that allowed him to "skip over" time; however, since he was INSIDE that device - he was no longer present as time continued for everyone OUTSIDE of it. The REAL plot hole in Back to the Future II is the changing of time travel theories. In the first movie, time is linear and the time machine enables you to move within that line (Much like in the H.G. Wells The Time Machine novel). In Back to the Future II, the theory changes to alternate realities.

Powercntrl is incorrect.

If you were able to travel to the future to see yourself, this would be perfectly reasonable assuming you eventually resumed your correct place in time.

Meaning? Well, let's say you depart on October 26, 1985 at 1:35AM, destined for October 26, 2015. You hang around in 2015 for a day, buy a sports almanac, look around, etc. You plan to depart on October 27, 2015 destined for the exact time you left - October 26, 1985, 1:35AM. Now, assuming that you make it back to your time, the timeline from that point will continue on as planned, and your future self will be right where they are supposed to be.

The caveat is, if you can't find your future self, one of three things happened:

• Your future self is in a location of which you are unaware.
• You died prior to the point in the future to which you have travelled.
• You never made it back to your own time.

None of this affects the plot of the movies in any way; they adhere strictly to these rules. This is just how it works. (The part in the beginning of Back to the Future I with Einstein is simple. Doc even explains it: "He skipped over that minute.")

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Since adding this writeup to this node, Powercntrl has attempted to dispute my dispute of his theory. In the last paragraph, Powercntrl makes the claim that BTTF I follows different rules than BTTF II with regard to spacetime mechanics.

This is simply not true.

Einstin's trip in BTTF I was one-way. Einstein went to the future and never returned to his normal place in time. That's why there was no "future" Einstein; he never made the return trip.

BTTF II does not deal with alternate realities; it deals with the corruption of the space-time contiuum by changing events in the past. Old Biff from 2015 goes to 1955, gives young Biff from 1955 the sports almanac, returns to 2015, and is erased out of existence. Due to the ripple effect, reality itself is changed to reflect past events. Excluding multiple reality theories, the new "Rich-Biff" reality is the only reality - the only reason it's referred to as an "alternate reality" is because Doc and Marty are already used to the 1985 they REMEMBER. The ripple effect hasn't caught up to them yet. (Listen carefully when Doc is sketching out the diagram on the blackboard.)

The exact same thing happened in Part I; Marty corrupted 1955 in Part I in a similar fashion as Biff did in Part II, except on a far smaller scale, and completely by accident. When Marty arrives back in 1985 in Part I, he finds his house and family have been changed drastically. Reality was altered from the past forward. Biff just takes this to an intentional extreme in Part II. They both play by the same rules.

THINK, McFly!

The original "plot hole" mentioned is simply a failure to follow the plot. In the original history, yes, Clara fell into the ravine. When Doc Brown goes back (but in the reality before Marty arrives), Doc volunteered to pick up Clara (the new schoolteacher) from the train station and evidently fell in love with her soon after.

When Marty gets to 1885 Hill Valley, he shows Doc the picture of his tombstone and Doc subsequently avoids picking Clara up at the station, seemingly unwilling to recreate any of the events that lead to his death. Thus, as in the original history, nobody is there to pick her up at the station and she has to get to her house all by herself...but her horses get spooked and she's about to fall into the ravine (again) when Doc and Marty save her.

Both Doc and Marty know the ravine as Clayton Ravine--because in the reality they've experienced Clara DID fall into the ravine. But since they saved her the ravine is named Eastwood Ravine when Marty returns to 1985, a cute joke if you've seen the movie.

The major plot hole in this series is in the second movie, which does, in its own way, deal with alternate dimensions or realities. Following along with Doc's explanation of what old Biff did, we have one timeline (or dimension) that is the standard (Earth-Prime, as it's called in "Sliders."). We are living happily in that timeline, traveling back and forth within it, trying not to change things because that would inevitably corrupt said timeline and possibly end existence, as Doc puts it.

So, one day in 2015, old Biff gets fed up with his life, steals the time machine and the almanac and goes back in time to 1955 to visit his former self and improve his life by making himself rich and famous. By doing this, he creates a new timeline, which, up to the point where he entered and changed it, was identical to the original timeline ("Prime"), thus allowing for Doc and Marty to go back to a time before all this happened in order to fix things.

The problem is this: Old Biff could not have traveled back to the original timeline with the DeLorean.

In the first movie, when Marty returns to 1985, he finds everything changed positively, while he is unaware of the events in the new timeline. He changed events in 1955, so when he traveled forward, he traveled forward into the new timeline he created, rather than the old one he came from in which Biff was still a bully and his family was generally dysfunctional. Therefore, the same situation would have occurred with old Biff. When he returned to 2015, it would have been the altered 2015, in which he was rich and powerful. Instead, he returns to the original timeline, where Marty and Doc are visiting a grown-up Marty and rescuing Jennifer. Following the premise laid out in the first movie, Biff wouldn't have been able to return to that reality, and therefore Doc and Marty wouldn't have been able to fix the situation, as they would have been altered along with everything else in the timeline.

The only possible explanation for this is that it takes a certain amount of "time" for the timeline change to take effect. In the first movie, Marty went to sleep shortly after he returned to 1985, so the time change may not have taken place yet, but by the time morning came, everything had been altered with the new timeline (The so-called "ripple" or "wave" effect).

This being the case, old Biff returned to the old timeline before it had changed, Doc and Marty got in the time machine and returned to 1985, where the timeline-change had already taken effect. Had they returned to 2015, it would have been an altered 2015. This seems to make sense, but there are two distinct problems:

1) Following this logic, Marty in the first movie would have become, in his sleep, the new Marty (the Marty who existed as a result of his time-traveling and the timeline-altering events he caused), which would have meant his "new" surroundings (nice house, parents who get along, lackey Biff) would have been familiar to him. Instead, he was terribly confused.

2) This theory requires that there is another type of time, one that effects time over time. If this didn't exist, any change you made in the timeline would take effect immediately, and the time traveler would find himself with new memories that had somehow always been there (this is dealt with surprisingly well in the cartoon "Invader Zim."). But, since this is clearly not the case in "Back To The Future", there must be some kind of ripple that starts at the place (time) of origin of the alteration and slowly moves forward, changing time to fit the new timeline. Under this logic, making a trip through time would have to take the amount of time that the actual journey takes, rather than being instantaneous, as it is clearly explained in the movies. So, even if we assume this theory is possible, as ridiculous as it seems, and disregard problem number 2, it still follows that Marty would have to be really stupid and out of it to not notice the way his family has always been (according to the altered timeline he created).

Either way, there's a problem. But, they are still great movies. Otherwise, they wouldn't even be worthy of this much discussion.