Revealing mistakes: When Scrat sniffs for his acorn, submerged under the ice, his saber teeth are clearly not modeled before he sinks them into the ice.
Continuity: When Sid is tossed from the branches to the ground back at his camp, some younger animals are shown, and among them, a trunked, long-necked animal, who is gone in one shot, and then instantaneously appears on the other side of the screen.
Factual errors: As with the first film, most of the animals shown did not live either in the Ice Age, in the same location or the same time period.
Revealing mistakes: When Crash jumps onto Diego's shoulders, as he is reaching the ground, slow motion of the film reveals that part of his face disappears.
Factual errors: Condors don't eat acorns.
Factual errors: While the two sea reptiles (Cretaceous and Maelstrom) were frozen in the ice, it is worth noting that in the era that they lived in, there was no place on Earth cold enough to generate ice.
Revealing mistakes: When Manny looks into the pond at his reflection right before meeting Ellie, a leaf lands in the water creating a ripple. Manny's reflection does not distort when the ripple goes through it.
Continuity: When Scrat's finished fighting the piranhas, he gets his acorn out of the one on the bottom of the screen. Yet the one that actually swallowed the acorn was smacked off-screen to the right.