Continuity mistake: When Anna's singing "The next right thing" she puts a bag on her shoulder, with the strap on top of her hair. After the camera spins round her, her hair is suddenly underneath the strap. This bears a strong similarity to the mistake in the original Frozen where Elsa's hair passes through her shoulder - might be a deliberate nod, or else animating hair around objects is difficult enough that shortcuts are often taken.
Continuity mistake: The two cucumber slices that Jesper puts in the palm of the Drill Sergeant change position between shots - in particular, in the close-up with Jesper walking away and putting the teacup in his hand as well, the two slices are side by side, while they are instead one on top of the other before and after. (00:02:25)Sammo
Continuity mistake: After the alien abduction, Emmet plans to lead a rescue mission and opens the gate asking "Who's coming with me?" During the sequence, the shadows change completely. At first he is not casting much of a shadow, then it reaches the metal doors, then it stops midway towards it. (00:20:55)Sammo
Continuity mistake: After Batman beats the hell out of Shredder, he's got blood all over his face. When the machine crashes down and launches him in the air into a pipe and he falls back down towards the camera, for a few frames you see his face again, and there is no blood. But in the very next shot before he falls into the chemicals, the blood on his face returns. (01:21:00)Quantom X