Continuity mistake: In the scene where the two kings are fighting, one of them pulls a swordfish from the table and after they calm down sticks the fish in his belt. In the next shot the fish has disappeared.
Continuity mistake: During the forest cottages' dressmaking sequence in the middle of the film, watch the backgrounds carefully. You will see backgrounds change themselves from one scene to the next (doorhandles disappear and reappear, plates reposition themselves on shelves, flowers mysteriously regroup themselves).
Continuity mistake: When Maleficent shows up her scepter's handle is either green, orange or brown depending on the shot. Throughout the movie this happens again a couple of times. If the change were due to the colour of the ball on top, the light should also be casting on her clothes and skin.
Continuity mistake: Flora is showing the fairies what changes to make on the dress, but when she points at the book and says "if you change it here" her right finger is missing the book and points at the table. When the shot changes the animation is fixed and her hand is now pointing correctly.