Continuity mistake: When Marvin Berry leaves the stage to call his cousin Chuck Berry, in Back to the Future II he stops and walks around a ladder that Mary climbed to get on the catwalk over the stage. Watch Back to the Future I and when he is talking on the phone there is no ladder behind him. In fact, that whole scene is different. The desk is different along with the phone and Marvin has his back to the stage in II whereas in I he is facing the stage. (01:26:09)
Continuity mistake: In the original BTTF the photo used to determine if Marty would exist in 1985 (the one with his brother and sister) is a wallet size photo. Yet when Marty in BTTF II (with the leather jacket) sees the other Marty from BTTF look at that photo and rush back to the dance, it's a regular size photo. (01:22:27)
Continuity mistake: In the first BTTF at the scene were George Mcfly knocks out Biff and takes Lorraine, Marty sees them while he is standing in front of a couple. When he goes through the couple to get to the band performing at the dance, the woman in the couple makes a noise and gets pushed aside as he tries to get through them. In BTTF 2 when the Marty back from 1985 is watching George Mcfly knock Biff out before he steals the Almanac, the Marty from 1955 stands in front of the couple again, but this time the couple leaves a gap for him to go through, and when he goes through the woman in the couple, she makes no noise and doesn't get pushed. It was as if she was expecting it that time. As well, the couple isn't the same.
Revealing mistake: When Marty and Strickland are talking in the Alternate 1985, pay attention to Strickland. Every time Marty is talking, you see Strickland moving his cheeks. He is mouthing Marty's lines. (00:42:37)
Factual error: Marty is pursuing Biff at the high school as the other Marty pulls up with Lorraine in Doc's car. In the parking lot, the car closest to Biff is a brown 1957 Chevrolet. The front grill and styling are distinct and unique to the 1957 model year. In November 1955, it would be plausible to see a 56 Chevy in the lot, but a '57 is a bit early. (01:16:42)
Suggested correction: Watched this scene carefully and compared photos of the 1956 and 1957 Chevy to the car in question. It is almost certainly a 1956 Chevrolet 210. The grill could be mistaken for a 1957 in the dim light, but the real giveaway is on the hood: the '56 Chevy had a single, centred hood ornament (as seen on the car in this scene), while the '57 Chevy had a pair of "rocket" ornaments on either side of the centreline.
Continuity mistake: In the high school dance scene, the guitar amplifier is standing on the floor. In the same scene in Back To The Future 1 it's raised up on some kind of box.
Continuity mistake: Biff's 46 Ford changes from a convertible to a hardtop with the roof cut off during some scenes (notice the shape of the windshield frame and vent windows).
Audio problem: As Marty and the sales guy are watching the sports flash thing, Marty makes a comment about the Cubs winning against Miami, and when the sales guy says, "Yeah really something isn't it? Who woulda thought," his lips don't match what he says.
Continuity mistake: The garage where Marty's truck is parked is very different in the opening scene of BTTF II than in BTTF I. The gardening tools on the wall to the left were different, and the brown wall siding in the back of the garage was not there in Part I. (00:00:38)
Revealing mistake: When Griff and his gang are chasing Marty on the hoverboards in a few shots after Marty is hanging off the back of the Jeep, when the shot shows the gang catching up, the Jeep goes through some wet places in the street, showing the camera car's tire tracks. They're not the Jeep's because the tire tracks are double-wheeled and the Jeep was not turning in that shot. (00:19:22)
Continuity mistake: When Marty is hanging onto the side of Biff's car as the sports scores are being said on the radio, Biff picks up the almanac to check them. You see him put it down in one shot, but when the shot switches to Marty's point of view, he puts it down again. (01:31:25)
Continuity mistake: During the dance hall scene, the first half of the guitar solo Marty plays (before the Eddie Van Halen section) is completely different to the one he plays in the original film. Whether this is just to give time for the jump sequence to take place or not is open to question, but all the same, although not many people would notice, it is a pretty obvious mistake. (01:26:00)
Continuity mistake: Near the end, when Marty is holding on to Biff's car and is trying to get the almanac, the direction of the almanac's cover keeps changing from shot to shot.
Continuity mistake: At the start of this film (and the end of the prior film), Marty and Jennifer talk with Doc who has just returned from the future to retrieve them. A shot looks over the rear half of the DeLorean at Marty and Jenn and we see the street behind them. Ignoring that Jennifer is now played by a different actress, there is a tree missing behind her, as is the truck with a camper-shell that was two driveways back. Parked in the street is a VW bus where a Pontiac Firebird was. Marty has also gained a wristwatch not present in the same scene in the earlier film. (00:01:40)
Continuity mistake: As the DeLorean lands in 2015 at the start, the car has silver center caps (between the wheel nuts) in the front and back wheels, but in the very next shot, they have changed back into the original black center caps. (00:06:00)
Continuity mistake: After the roof scene in alternate 1985, the time circuits show the Nov. 12, 1955 readout before Doc enters it. (You can hear him still pressing the buttons afterwards). (00:59:00)
Continuity mistake: When Marty gets out of the water after jumping from the hoover board, the board is a bit far from him. In the next shot it is right next to him, to help him pick it up and leave.
Factual error: In 1955, Doc says "Sunrise should be in around 22 minutes." This wouldn't be possible as the sky is fully dark (except for a slight bit of light on the other side). If only 22 min from sunrise, even on a stormy overcast morning, the sky would be fairly light by then.
Continuity mistake: At the start when the DeLorean crashes into the line of six bins on the driveway one of the bins is half open. It is one from the right. In the next shot when Dr. Brown gets out the bin that is half open is two from the right. Then a bit later when the DeLorean comes out of the driveway all the bin lids are closed. The bin lids were never closed all through the scene.
Continuity mistake: When Marty is being chased by Griff's hover board gang, Marty grabs rope from a car. Just after, he has to avoid an oncoming car. One second he's holding the rope, the very next shot as he goes over the bonnet, the rope's gone. (00:19:38)
