Corrected entry: When Doc, Marty and Jennifer go into the future, they disappear above the Mcfly home, but when they arrive in 2015, they are outside Hill Valley (although after they disappear into the future there is a long 'journey' when the credits are showing, with enough time for them to get out of Hill Valley, but after the 'journey' the car makes the swooshing noises it does when it arrives somewhere, so this was just for the credits).
Corrected entry: When Biff is at the Enchantment Under the Sea dance he tells principle Strickland that he is not old enough to drink alcohol. At Biff's hotel the movie that plays says that he won at the track on his 21st birthday in 1958. When Doc stole the newspapers from the library there was an article about Biff's winnings dated in March of 1958. If Biff was 21 in March of 1958, then he was 18 in November of 1955, and since the legal drinking age was 18 in 1955 he was, in fact, old enough to drink alcohol.
Corrected entry: At the end of the film, as the DeLorean gets struck by lightning, Doc goes back to 1885. We then hear Marty reading from the letter that the lightning strike damaged the flying circuits on the car. So how did he land it in 1885 from the 40 feet altitude he was at when struck by the lightning, if the car couldn't fly in order to land safely? (01:39:51)
Corrected entry: When Marty from Back to the Future I leaves George and Lorraine out the back door of the gym he opens the door so hard that he hits Marty of BTTF II and knocks him down. Watch Back to the Future I and see how far Marty actually opens the door. He barely opens it enough for himself to fit through. In other words, he would have never been able to knock himself out.
Corrected entry: Griff and his gang crash into the courthouse on their hoverboards, yet a minute later, the little girl has the same hoverboard Griff was riding. Even if Griff flew off the board, it would still land on the other side of the water or in the water. The little girl is on the opposite side.
Corrected entry: When Marty is at the Enchantment Under the Sea dance at the end of the movie, he's trying to get the sports almanac from Biff. But then Mr. Striklin takes the Magazine from him and goes to his office, and throws it in the garbage. Marty then immediately gets it out, only to realise that it is just the almanac cover, with an Oh La La magazine inside. Therefore the coverless almanac is still in Biff's hands, so Marty crumples the cover, throws it on the ground, and runs after Biff. Then, When he is chasing after Biff again to get the REAL magazine, the cover is once again on the magazine, in Biff's hands. (01:20:48)
Corrected entry: At the end of BTTF, we learn that Doc is alive because he did indeed find Marty's letter. And we know that he had to tape it together because he ripped it to pieces. Now at the the end of part 2 upon seeing Marty reappear after he has sent him back to the future he faints. Now wouldn't this alter the timeline because he never goes through the trash to get the letter therefore he won't be prepared in the future with his bullet proof vest? (01:41:47)
Corrected entry: Considering the sports almanac contains 50 years of statistics in all major sports, it is very small and thin, about the size of a magazine. This would work if it only contained major sporting event results (super bowl, world series) but obviously it doesn't. It has results from horse races in small towns like Hill Valley listed and regular season college football scores. The font size of the printing in the book would literally have to be microscopic in order to contain all the info it does. Even college football alone, listing just Division 1 teams, would require several hundred pages.
Corrected entry: In the scene where Marty is watching his other self talking to his parents (his other self just played Johnny B. Goode), he is watching through the door, when suddenly Biff turns up and they argue. When they are about three feet away from each other (just enough space for a door to be opened) you see Marty blinking his eye, because he expects the door to be slammed open, and the Marty from the first film rushes out.
Corrected entry: This is the part in the very beginning when Doc takes Marty and Jennifer to the future. Wouldn't the future be without Marty and Jennifer because they left in 1985 and must have been missing all that time. From 1985-2015. Thus, there would be no way in heck that they would have existed in 2015, and no way that the 1985 Jennifer would have seen herself or her house, family etc.