Continuity mistake: After Ralph destroys the cake and it goes all over the place, we cut to a wide shot. In this shot, to Gene's right, there is a small amount of cake on the floor. In the following shot, the amount of cake has doubled. Also after Ralph destroys the cake Mary is holding the people that were on top of the cake even though Ralph just destroyed them. (00:13:10)
Continuity mistake: When Mr. Leonard is closing up Marketropolis, there is nothing behind his car, but when he begins to back out of the parking lot seconds later, a shopping cart has suddenly appeared behind his car. (00:00:20 - 00:01:05)
Continuity mistake: At the end of the movie, before the Guardians leave, Jamie rushes over to hug Jack. In the first shot, the top of his head nearly reaches Jack's ribcage. However, in the following close-up shot, Jamie is almost at the same height as Jack's shoulders. (01:27:30)