When Liz and Abe's plane crashes, it sinks far too quickly to be realistic. Also, from the sheer amount of force the plane hit the water with, both should easily have died. Obviously done for dramatic effect, but still a mistake.
When the "Dragons" are being released around the world, you see a baby carriage nearly falling into one of the cracks that forms in the ground, only to be saved at the last minute. The baby-crying sound effects were actually provided by Selma Blair, who does the voice of Liz Sherman (and also played her in the live action film), after the makers realized she could do a perfect impression of an infant crying.