When Marty and Doc are following Biff to get the sports almanac back from him just before the tunnel scene you see the shot of Marty sliding down the side of the DeLorean, because of the hover conversion that Doc had done the DeLorean gives the impression that is it hovering but if you look in the bottom left of the screen you can see the wheels that the DeLorean is running on, you must look carefully and wait for the right light to see this. [Already submitted - twice.]

In one scene near the end where Marty is riding on his hover board next to the DeLorean, you can see the casters under the car that keep it "hovering" a few inches above the ground. [Already submitted.]

In Back to the Future 1 after Marty goes to 1955, you see a sign that says "Hill Valley 2 Miles". Later in the movie, Marty talks to George and Lorraine then walks out the door. The next scene you see Marty with Doc in his 1985 explaining that he needed to change his clothes, and than there is the whole sequence where Marty goes back to 1985. In 1955, in Back to the Future 2, Marty is standing outside the gym when Biff approaches him. Marty is knocked down by his earlier self, and Biff steals the Almanac. Then Marty steals the Almanac, burns it, sees Doc get struck by lightning, receives the telaeraph, runs 2 miles back to Hill Valley, just to meet Doc after his previous self goes back to 1985. How is it possible for on Marty to do the thing previously stated, while the other one dresses and drives to the Clock Tower, taking up the same amount of time? [You explained the nit yourself. We don't know how long it took for Marty to change into his 1985 clothes in Part 1... we only know that according to Doc, Marty was late in meeting him. Marty may have gone back to Doc's house to get his clothes, adding some time.]

When 1985 Marty first puts on the "future jacket," the sleeves are really long (can't see his hands or anything), but after Doc comes up (and before he pushes the button to make it fit) you can see Marty's fingertips, and the jacket only goes up a short bit. [Marty is holding the sleeves up. That's why you see his fingers.]

In the Cafe 80's scene, when the future Marty has ordered a Pepsi and Griff walks in, the Pepsi bottle changes from in his hands to on the counter several times between shots. [He is holding it the entire time. There are other bottles on the counter.]

The two theories of time travel displayed in the Back to the Future series seem to conflict with each other. In the first movie, Marty changes history to create a future where he was never born, and as a result he begins to fade out of existence. In the second movie, Biff changes history to create a future where Marty is away at boarding school, but rather than fading into his new timeline, Marty stays exactly the same. There are now two Martys, one from 1985 (Marty 1) and one from 1985A (Marty 2). If that's the case, then Marty should have stayed exactly the same in the first movie (Marty 1) and returned to an alternate universe where his other self (Marty 2) was never born. [The first movie also establishes that the irreversible changes in the timeline are not instantaneous. Marty was in 1955 for a week before he started fading away. He was only in 1985A for a few hours.]

When Marty is talking to the Doc when he is in the back of Biff's car, it shows the present Doc with the past Doc's hair (i.e. the actor has the wrong wig on). It cuts back to Marty, then back to the Doc, where he still has the past Doc's hair. When it cuts back to the Doc a third time, he has the present Doc's hairstyle. [No such thing. First, since the only two scenes Christopher Lloyd played "young Doc" (when "old Doc" runs into him and when Marty runs around the corner) both took place at the clock tower at night, there would be no reason for the actor to wear the wrong wig. Secondly, "young Doc" has wavy, blond hair while "old Doc" has white hair. The Doc talking to Marty on the walkie not only has white hair, it's the same white hair. The only difference in the shots you're mentioning is that the wind is blowing in the third of the shots.]

During the scene where Marty has to duck and move past the car with his other self and Lorraine inside the car, he hears his other self ask Lorraine if she smoked too, in which she replied, "You're beginning to sound just like my mother." Then Marty hears his other self say, "Yeah right.". Problem is, in the first Back To The Future, after Lorraine said that, Marty never said "Yeah right." [We don't know that. In the first movie, after Lorraine says her line, Marty gives her a quick look and it cuts to another scene. He may very well have said "Yeah right" after the cut.]

When Doc runs to the end of the alley and takes out his hi-tech binoculars you can't see Marty by the De Lorean down the alley. [This is because Marty is bending down into the car, out of view.]

When Doc and Marty are in Doc's house in the alternate 1985, Doc sets up Einstein's doggie bed and the dog jumps in. From one angle he starts to turn around to his right, but in the reverse shot he turns to his left. [Have a look next time you see a dog doing this - the circle rapidly one way, then reverse, then reverse again, and finally settle down. That's exactly what Einstein is doing.]

Every time the same actor is playing two people (eg old Biff and young Biff), the line from the splitscreen is covered by something (the framing on the car, a pole). [This isn't trivia, it's just vague guesswork - when Marty picks up his 'son' behind the bar of the diner, or when old Marty and his two kids have pizza there is nothing to 'hide' the split, it just goes through the frame somewhere between them.]

In one scene, Doc Brown says that the year 1955 might be the junction point for the entire space/time continuum. 1955 WAS a big year for space travel, as it was the year that President Eisenhower entered America into a competition to send up a sattelite by 1957.(Our sattelite was called Project Vanguard; Russia won with Sputnik). Thus the space race actually started in 1955. [Interesting, but not really related to this movie, or even time-travel in general.]

Doc and Marty learn the date when Biff was given the Almanac. It turns out that this is also the date of the events in the first film. Doc then surmises that they will not only have to avoid detection by Old Biff but also by their 'other' selves. All that considered, does it not seem a little reckless to return to that date? They have a Time Machine, and the book is useless to Biff until he turns 21 which would be 1958 at the latest. That's a whole three years and Doc could have chosen from any day he wanted to retrieve the book but he picks the day where they run the greatest risk of screwing up time even more. Given that he's always lecturing on the consequences of messing with time, and that their entire future depends on him succeeding, it seems a little out of character for Doc to not even consider the possibility that they go back to a different day. [It's a calculated risk on Doc's part. On that day, they know where Biff is, they know that the almanac will be out in the open and far easier to get. If they leave it until later, Biff will have had a chance to hide the book away somewhere, making it potentially impossible to locate. And while Biff might not yet be twenty-one, it wouldn't preclude him doing an illicit deal with somebody over that age to place bets on his behalf, thus altering the future. If they go back to the day when he gets the book, it avoids any possibility of Biff altering the timeline. It does open up the possibility of them causing problems, but given that they're both aware of the situation, plus know precisely where their prior selves will be on that night, the risk is relatively minor compared to allowing Biff to hold onto the book for any extended period of time. As for considering this, Doc undoubtedly did, but showing a long-winded justification on-screen would have been somewhat dull and would simply have broken up the flow of the film.]

According to Emmet brown, if someone meet with his alternate ego, it will faint or create a "time paradox" that will destroy time, however Biff talks and interact with his alternate ego with no problem. [First, Doc says this as a warning to Marty; that it *may* happen, not that it *must*. Second, Biff *does* create a time paradox that destroys time. That's why there is an alternate 1985 when Doc and Marty go back. Biff has destroyed the original timeline.]

After Marty burns the almanac in 1955, he looks at the 1985 newspaper that he has with him and sees that it is changing. One of the stories that changes is Nixon to Seek Fifth Term; Vows End to Vietnam War by 1985 to, Reagan to Seek Second Term; No Republican Challengers Expected. Reagan wasn't looking for a second term in 1985 because he won it in 1984. [The paper is not from 1985, he just got it in 1985.]

You have to really listen carefully but when the Doc says "Griff's gonna ask you about tonight" he says "Biff" by accident. [Character mistake. The names are so similar, and Doc is more accustomed to saying "Biff".]

As Marty sees his other self talking to his parents, Biff appears and challenges Marty to a fight. When Marty walks away Biff calls him a chicken. Marty walks up to Biff and when he says "Nobody calls me chicken" he gets hit by the door and even though you hear the word chicken, Marty's mouth doesn't move when he says it. [Marty's mouth moves when he says the first part of the word, then he is getting hit by the door as he continues talking, so that's why his mouth can't be seen moving for the rest of it.]

When Marty is back in 1955, he goes to Strickland's office to get the almanac back. He looks through the window, and sees Strickland sitting in his chair with the almanac. He is looking through some sort of mesh on the window. When he goes into the office, the mesh is gone. [The wire in the glass is always there. It can be seen by looking closely. It's just not as obvious in shots where the window is in the background because the wire is thin and the silver color of it tends to make it blend in with the glass at a distance.]

When Biff and Marty discuss the Almanac in the Alternate 1985, a magazine is visible. This is the March 1989 issue of "Mustang." [They are discussing a "book" that is brought back from the future while in an alternate universe of sorts, but another book dated a few years ahead in time is out of the question? They have a time machine at their disposal, and could have brought back any item they wanted, as it is illustrated that they did indeed travel forward in time to an "antique" shop in the future.]

You'll need slow-mo and pause for this one. When Griff's three mates throw down their hover boards they actually throw them beyond the camera, then digital super-imposed ones land in front of them. Watch closely at the girl's board (on the right) it's transparent, then the guy in the middle jumps beyond the camera and again super-imposed legs land on the hover board. [Slow-mo AND pause? This is so difficult to see even when using slow-motion that this certainly does not class as a mistake.]