Corrected entry: When Marty shows Doc the flyer from 1985 about saving the clock tower, this gives them the time that the clock will be struck by lightning, 10:04pm on that coming Saturday (11/12/55). However, the main problem here is that the time is only given in hours and minutes, and since lightning moves at the speed of light, an entire lightning strike lasts only fractions of a second. Doc and Marty have no clue as to what second the lightning will strike during that minute, and it isn't given a thought. In reality this would cause a tremendous dilemma if the Delorean had to pass at a precise second. And since the clock on the tower lacked a second hand, they would need a sychronized watch to determine the second the strike occurs, even if they knew it. In the movie it is assumed the strike occurs at 10:04:00, which is fine, but for more realism they could've added a second hand to the clock to eliminate this plot hole. It would have been stuck in place as the other hands after the lightning strike.
Corrected entry: Anyone else find it ironic that Einstein the dog was the world's first time traveler, while the real Einstein was the one who said that time travel is impossible?
Corrected entry: In the scene where Marty is playing Johnny B. Goode, and someone cuts into George and Lorraine's dance, Marty starts disappearing. Then he comes back, pushes the guy down, and kisses Lorraine, resulting in Marty reappearing. But George did that on his own, without Marty interfering, so why should he have disappeared in the first place? He was always going to come back and assert himself - it's not like the timeline was being changed.
Corrected entry: Mayor Red Thomas in the 1950s based on his picture, looks to be around age 50. However, in 1985, when he is a bum, he still looks about the same age, even though he should be around 80 years old now. Granted, some people age better than others, but it is doubtful that an old man living on the streets would even survive for very long, let alone age gracefully.
Corrected entry: When Marty first enters Lou's cafe in 1955, Lou is visibly angry at Marty just because he won't order something right away. However, he doesn't seem to care that one of his paying customers, George McFly, is being harassed by Biff and his gang and told never to come in there again. You would think Lou would tell Biff and Co. to knock it off or else be asked to leave.
Corrected entry: This one is tricky but important in view of Doc's concern about doing anything that will alter the future. The lightning rod on the clock tower would have been connected to ground with a thick cable. Doc would have had to disconnect this cable to allow the current from the lightning to flow into his cable instead and hence to the time machine. We now know that a lightning strike is a result of a complex interaction of electric potentials between charges in a cloud and charges in the ground below. By disconnecting this grounding cable this interaction would have been disrupted, causing the lightning to strike at a different time or strike a different object on the ground.
Corrected entry: When Marty travels back to 1955 the DeLorean first strikes a scarecrow, then drives at high speed into a barn and finally crashes through the barn door to escape. Later, when it returns to 1985, it crashes into a movie theatre front before it can stop. After all this mayhem the DeLorean doesn't have as much as a scratch on its nose.
Corrected entry: After Marty returns to 1985, he discovers that he now has the new Toyota truck he wanted, while the rest of his family is forced to share one car. Why would Marty, the youngest of the siblings, who is still in high school, have his own brand new truck while his older siblings and both parents have to share one other vehicle?
Corrected entry: After Marty reunites his parents, he and his siblings all reappear in the photo and all is well. However, in order for Marty and his brother and sister to exist again, it would mean that Marty's parents would have to have sex at the exact same moment all three times to conceive them. Even if they were a few seconds off, it wouldn't be the exact same three kids. Similar maybe, but not exact. Now that George is more successful, he will be doing many things differently in his life so the chances of him and Lorraine having sex at the exact same millisecond all three times to have those exact three kids is beyond astronomical.
Corrected entry: When Doc is having the DeLorean do the burn out to get the car up to speed, the car is spinning its wheels up to 65 mph and Doc releases the brake. Now the car takes off, but the car would lose most of the speed the tires had built up as it is starting from essentially a dead stop even though the speedometer still shows 65 mph. Think of it this way, the back tires may be moving at 65 mph but the front tires are not. There is no physically possible way for a car to jump from 0 to 65 mph instantaneously using only its tires no matter how fast they were rotating. Even an F/A-18 needs a catapult to get that kind of speed so quickly. (00:21:35)