Deliberate mistake: Manny refers to the pirate rabbit as the Easter Bunny, even though Easter never existed in prehistoric times. (00:33:55)
Suggested correction: And mammoths didn't hang out with sloths and smilodons either. It's creative license.
Deliberate mistake: When Ralph and Vanellope are practicing driving, Vanellope loses one of her upper teeth. The tooth magically reappears again for the rest of the movie. (00:57:30 - 01:20:20)
Deliberate mistake: When Julien is about to pull the switch to turn the power off in the Monte Carlo casino, the sign above the switch says "LE POWER." Monte Carlo is in Monaco, where the language is French, so the sign should be in French. Obviously "THE" is in French as "LE." But "POWER" is not in French. The sign should have said "LE POUVOIR." (00:10:15)