Continuity mistake: When the lightning bolt hits the clock tower in 1955 and sends the DeLorean back to 1985, Doc Brown gets up and looks at the clock tower. What happened to that awful lightning storm of only a few seconds earlier? Not even a trace of wind is present in Doc's hair. (01:36:55)
Visible crew/equipment: When the clock tower ledge breaks, Doc Brown slips and loses his grip on the electric cable. In the next shot the stunt wire pulling the thick electric cable towards Doc's pants is visible. (01:37:50)
Continuity mistake: When Marty is at the "Start" line waiting for the alarm clock to ring, he moves up his return time and the engine stalls out. Next we see Marty turning an ignition key with several other keys on a chain like the ones used on ceiling fans with the little balls and a plastic fob with the paper insert that reads 555-1138 Out-A-Time on it. After Marty arrives back In 1985 in town square, he pauses and gets out for a moment. While returning the the car he puts the DeLorean in drive and again the car stalls out. Again we see Marty restarting the DeLorean, we see a different set of keys. The key mysteriously changed in the time travel to an after market type with a thin wire ring on it, no key fob and the other keys are missing. (01:38:43 - 01:42:44)
Continuity mistake: When the DeLorean sets off for the lightning strike, you can see it leaving tracks and spray on a wet road, later there is a close up of one of the wheels, which shows the road to be dry. Throughout this scene the road appears to alternate between wet and dry, during what is supposed to be a storm. (01:39:00)
Factual error: When Marty hits his head on the DeLorean's steering wheel, the car's horn honks. This is inaccurate to the design of real-world DeLoreans, as a DMC-12's horn button is actually located at the end of the turn signal lever rather than in the steering wheel. (01:39:27)
Suggested correction: You can't see his left hand and he could have accidentally pushed it when he hit his head. Or Dr. Bown customized the steering wheel so the horn is in it, like he customized the entire interior of the car.
I thought the point was that the car was so unreliable that when hit his head on the steering wheel, the horn went on. Makes sense to me. I own a DeLorean by the way.
Continuity mistake: When the Doc is trying to pull the cable to connect it, the cable is stuck. And when he pulls the cable hard, the other connection breaks off. Watch when it breaks off, you can see that after Doc pulled it, the cable gave him more length and would surely get Doc's arm to the other cable. When they show the Doc a second after, he hasn't moved one bit. (01:39:35)
Continuity mistake: Inconsistent mileage progression on the DeLorean at the beginning of the movie has already been noted. However, mileage when Marty is going back to the future is also inconsistent, both in those scenes and with the beginning of the movie. As Marty is driving toward the cable, the mileage is shown as 33051. Just as Doc begins to slide down to reattach the cable, the odometer is visible again and shows 33044. These scenes were obviously filmed out of sequence, and were filmed before the beginning scenes (32994, 32064, etc) of the movie. (01:39:55)
Revealing mistake: As the DeLorean's tyres start igniting as it is about to travel back in time, the flames are not coming from the tyres, but from some ignitors attached to the car. (01:40:36)
Revealing mistake: When the DeLorean is struck by lightning near the end of the film, if you look closely, you can see that there are two people in the car, when it should just be Marty. You may have to look closely, but you don't need to zoom in to see it. Also, since they never re-shot this scene, you can see it in all three Back to the Future films. (01:40:40)
Continuity mistake: In the first scuffle between Marty and Biff in the school cafeteria, they both grab a hold of each other's shirts until they were stopped by Strickland, but in the next shot, Marty is not holding on to Biff's shirt. (01:40:40)
Revealing mistake: When Marty is skateboarding and being chased by Biff's car, Marty's stunt double is noticeable because his wig is bulkier and darker coloured than Marty's real hair. He looks just like the Trololo guy from Youtube. (01:40:50 - 01:41:25)
Continuity mistake: When Marty is writing the letter to Doc before he goes into the future, the word "disaster" is the only word in the last line. Yet when Doc shows Marty the letter when it has been all taped up, "terrible disaster" is the last line. Also, the handwritring in each letter is different (i.e. Marty's signature). They are two different letters. (01:40:55)
Continuity mistake: Throughout most of the film, the licence plate on Doc's car reads 8N 39742, but after the DeLorean travels back to 1985, it changes to 7F 42857. (01:41:31)
Continuity mistake: At the end of the movie, when Doc Brown leaves Marty at his house, he then backs up the DeLorean, turns the car around and passes in front of Marty doing 35 mph at the most, but just as he leaves the frame you can hear the swishing noises the car makes when it travels through time. No way could Doc have reached 88mph. (01:42:00)
Continuity mistake: In the scene after Marty returns to 1985 he jumps out of the DeLorean to verify he's back and then jumps back in the car to go save Doc at the mall. In the shot where he's putting the car in gear, you can read part of the yellow "Last Time Departed" display on the time circuits as "1985, 1:20AM", and in the shot where he's trying to start the car, you can read "Oct". It should read "November 12, 1955, 10:04PM" since that was the time he just left. On top of all that, the display appears to relate to when Einstein traveled a minute into the future (you can see when Doc shows Marty the time circuits after he lets Einstein out that the "Last Time Departed" is "October 26, 1985, 1:20AM"), not when Marty traveled back to 1955 (October 26, 1985, 1:35AM). You could argue that the "Last Time Departed" display is not working properly, but Doc uses Marty's last time departed (October 26, 1985, 1:35AM) to set Marty's destination time when he's returning to 1985. (01:42:40)
Continuity mistake: Lorraine Baines' hands are on her hips, a brief cut to Marty and back and she now holding a cup and saucer at chest height. You could argue she had enough time to pick it back up, but this would seem odd as she's only just put it on the table. (01:43:55)
Revealing mistake: When the DeLorean travels back in time after Marty returns to 1985, the light emitting from the DeLorean does not actually come from the DeLorean, but from the side of the screen instead. (01:44:16)
Continuity mistake: The second time the Libyans kill Doc, after the DeLorean disappears, the kiosk is in flames. A frame later the flames are gone. (01:44:19)
Revealing mistake: At the end, the DeLorean hits the left dustbin and comes to a halt - you can easily see that it's not Christopher Lloyd driving, it's someone with a much bigger build, wearing an awful white wig. Further, he isn't wearing sunglasses until he gets out of the car. (01:45:55)
Visible crew/equipment: At the end of BTTF they all pile into the DeLorean which reverses up to the camera where the matte box and what looks like the top of the cinematographer's head are reflected in the chrome number plate. (01:46:50)
