Continuity mistake: On the jousting scene where William loses his helmet, he has a monstrous bruise under his right eye (in the late afternoon). That night at the banquet, there is no trace of the bruise. So far as I know, even a black eye doesn't completely heal that quickly. (00:49:50 - 00:55:25)
Continuity mistake: Notice Marty's hair in the scene when he's playing "Johnny B. Goode." It's quite larger than when he says, some seconds later, "I guess that you're not ready for it yet." That's because when he says that, it's a recycled shot from the original BTTF, whereas most shots showing he's playing the guitar are newly made for BTTF2. However, Marty's hair is considerably longer in the new shots. (01:27:19)
Continuity mistake: When Ace is trying to work out what Einhorn and Finkle have to do with each other, his dog sits on a photo of Finkle and its hair does not cover the face, the shot moves to Ace and then back to the dog and now its hair is covering the face of the photo without even moving. (01:03:30)
Continuity mistake: After Mike and Ned fight with lightsabers, when they are in the kitchen Mike's wedding ring moves from his left hand to his right hand and back again, depending on the angle of the shot. (00:21:05)
Continuity mistake: When Hutch tackles Starsky to the ground after his gun goes off in the disco, Starsky's badge falls to the ground beside his head. Hutch grabs it and holds it up, telling people to calm down, but when the shot returns to Starsky the badge is still there next to his head. (00:49:40)
Continuity mistake: In the scene where Jonathan picks up the scarab, it breaks open and the beetle inside starts to crawl under his skin. We see Brendan Fraser tear Jonathan's shirt and cut the beetle out of him. However, in the very next scene, we see Jonathan walking into the temple, his shirt is intact and there is no blood to be seen. (01:37:05 - 01:38:30)
Continuity mistake: During the scene in the mall when the girl is in the dressing room, she keeps putting on more layers of clothing. But as they are shooting different shots she will have a hot pink shirt on, then it is back on the hanger, and then back on again. It switches back and forth many times. (01:00:50)
Continuity mistake: Luca and his friend are chasing a bus and come down an old dirt road, Luca in a side car with a dog in his lap. The next shot, there's no dog, then the next shot the dog is back in his arms again.
Continuity mistake: When the Mystery Men smash their "Magnetic" Herkimer bus through Casanova's Castle's main gate you can see a number of the lights mounted to the front of the bus are smashed, however, in the next couple of front on shots, you can see that all lights are working and intact.
Continuity mistake: When Robbie and Julia are making their friend the limo driver run through the obstacle course to prove his driving ability, you can clearly see both right-side hubcaps come off the car. Then, just a few seconds later, the hubcaps are back on the limo.
Continuity mistake: In one of the ice skating rink scenes, the camera looks at John Cusack and there is no snow falling. It then cuts to Kate Beckinsale and it is snowing heavily. (00:09:25)
Continuity mistake: When Clouseau parks in front of the ministry of justice, he breaks the hood of two police cars. A few shots later, when we see him entering the building, only one of the cars is broken.
Continuity mistake: When everybody is at the rehearsal for Grant and Julia's wedding, when Bernie does a toast to Julia and Grant, watch the level of water in Roz's glass, it changes without her even touching it.
Continuity mistake: When the family is getting into the car to go to the wedding one grandmother says to the other "let me in". The grandmother gets out to let the other grandmother in but the first grandmother never gets back in the car, she just pretends to. You can see her hiding behind the cars as it backs down the drive. Both grandmothers are in the car when they see Long Duk Dong on the lawn.
Continuity mistake: Look at the dirt when Herbie backs away from the nose of the newer Beetle, between the races out in the desert. Although Herbie drove straight up to the newer Beetle, tire marks can be seen where the crew moved the car back and forth to get him lined up.
Continuity mistake: When Napoleon is waiting while Rico makes a sale, he checks his watch to see how much time he has before the dance. The first time he checks it, the date on the watch indicates Thursday July 17. When he checks it again a few minutes later, it shows Monday July 21.
Continuity mistake: When Vanessa is outside of the beauty shop playing her keyboard with her headphones, and Willie is talking to her, she takes off her headphones and puts them around her neck. In between shots the headphones disappear.
Continuity mistake: When Fairy Godmother is throwing the books behind her, the book "Snow White" lands on the other books. "Snow White" noticeably changes position between two shots. (00:41:15)
Continuity mistake: When Cage's character offers the money for his brother and the brother is in the car about to get crushed, the back window gets broken out twice. (00:15:55)