Continuity mistake: In the third segment of the movie we see Davis, Yolei, Cody and their Digimon playing on the beach. In the wide shot when we see all of them playing we see that Davi's Digimon is in his "rookie" form, Veemon. When they show a closeup of him and Davis together, Veemon is now in his "in training" form DemiVeemon. Then they show them all playing again and he is now Veemon again.
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)
Plot hole: When Astrid gets on Toothless for the first time, Toothless takes off uncontrollably and tries to scare her. Hiccup seems to have no control over him at this time. How is that so if with the new tail fin, Toothless cannot fly without Hiccup's precise control of the tail fin? That whole sequence would have fallen apart. This mistake was even admitted to on the DVD commentary. (00:53:35)
Continuity mistake: When everybody goes into Branch's bunker the King is wearing clothes. A few seconds later during hug time he only has on underwear.
Plot hole: Joy and Sadness are stuck outside of the control center. They are trying to figure out how to get back, and encounter maintenance workers who are discarding old memories. The maintenance workers show that they have the power to send memories back up to the control center to be played. Why couldn't they send the core memories that Joy had back up the same way? Better yet, why not use that method to send Joy and Sadness back up to the control center? The director of the film is even aware of the plot hole, and said "Yeah, well then we wouldn't have a third act," before explaining how the idea of recalling memories was added in later, "box[ing] [the screenwriters] in a corner a little bit."
Suggested correction: Even if they do send the core memories up to headquarters, they wouldn't be able to get joy and sadness through the tiny gap that the workers send the memories up. Joy has to be in headquarters for Riley to be happy.
This mistake is large enough that the director is aware of it. I think that more than qualifies it to be on this site.
Suggested correction: Joy is a control freak, she wants to return the memories herself. She doesn't even imagine that the workers can do such a thing.
Continuity mistake: When Jingle, Jangle, and Mrs. Claus pay a visit to Mother Nature, Mother Nature calls her sons beside her - Snow Miser and Heat Miser. She then turns to Snow Miser and asks him to allow a little snow fall in the South, and then turns to his brother, Heat Miser, and asks to allow just "one Spring day at the North Pole." The words are correct dialog, but she should have said each of those lines to the OTHER brother. (00:39:40)
Other mistake: When the switch is thrown to electrocute Terrence and Phillip, it's pulled downwards. A few shots later, we see Cartman jump in to save T and P by turning the switch off. He also pulls the switch downwards instead of pushing it upwards. (01:06:05)
Continuity mistake: Just before Flynn cuts off Rapunzel's hair, there is a shot from behind him and he reaches up with his right hand to push her hair behind her ear. His arm is visible up to his forearm and the shackle is nowhere in sight. However, in the next, wide shot, the shackle is suddenly up around his wrist. (01:01:20)
Plot hole: Scar tells the pack he didn't make it to the gorge in time to help Mufasa. However Zazu was with them at at the gorge. He could have easily told Serabi or any of the other lions on the numerous times he spoke with them, exposing Scar.
Suggested correction: Actually, Zazu wouldn't honestly say that Scar was lying; he left Scar at the gorge, but for all he knows, when Scar talks about not getting to the gorge in time, Scar could just mean that he couldn't find a safe path into the gorge to help Mufasa and Simba escape.
So Scar would say he couldn't get to Mufasa in time. Not the gorge.
Suggested correction: But it wouldn't have confirmed that he killed Mufasa.
Audio problem: On the first level of the video game, after Velma brings up what she remembers what Eric said about the Scooby snacks in the game, you hear Daphne talking but you see Velma's lips moving. (00:01:00)
Continuity mistake: When Barry gets stuck inside for the first time, he hangs onto the drapes. His arm is straight across, but in the shot behind him, his arm is now bent and raised and above his head.
Continuity mistake: Before Smee gives Hook a shave they hear Tick-Tock Croc approaching, and when Hook nervously spins around to look at the water, note that he has a left hand and his hook is at his right, but it should be the opposite way. (00:24:20)
Continuity mistake: Near the start, Mirabel is given a basket with items such as bucket and spade, windmils etc. When given the basket the buckets are towards her. When the shot changes the buckets are away from her. (00:07:15)
Other mistake: When Nebbercracker is on the stretcher and is being wheeled away, the grass pulls off one of the last wheels. When the stretcher is loaded into the ambulance both of the back wheels are intact.
Continuity mistake: Lotte barges in the pizza place and carves her name onto Shaggy and Scooby with her sharp nails. LOTT on Shaggy's shirt, and the E in Scooby's fur. They run out the door and then come back to pay for their food. Suddenly the rips in Shaggy's shirt and the scraped off fur on Scooby's chest have vanished. (00:23:45)
Continuity mistake: At the beginning of the movie, Itchy comes to heaven in a teal colored shirt. When given a halo, he is in a blue shirt (the shirt is for heaven, but not given to him at that moment). When Itchy runs to Charlie right after that, his shirt is teal again. When Charlie tells Itchy he is dead, that's when the shirt changes to blue again (purposely).
Factual error: In the beginning of the film, the Dowager Empress Marie states that the year is 1916 and that they are celebrating the 300th anniversary of their family's rule. The 300th anniversary actually took place in 1913. (00:01:05)
Continuity mistake: In the scene where Grug is chasing after Guy, they both wind up stuck in a tar pit. After successfully escaping they are covered in tar and Grug even gets himself stuck to Guy. In the next scene everyone is running from the exploding ground up between the mountains and both Grug and Guy are completely clean and free of tar.