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 Felix is about to receive his first medal, a few things change in a cut to a close-up. The building has grown much wider (32 notches under the roof compared to 22 before), giving the Nicelanders room to carry Ralph before throwing him, when previously Ralph was already against the edge. Additionally, a pair of large clouds has popped into the middle of the screen to cover the medal before it appears, which may have been considered too distracting to include in the previous shot. Later on, the medals which are engraved with Felix's name in-game instead bear a bas-relief hammer and gain a white stripe through the center of the ribbon when shown in 3D, a rather drastic change for what is only meant to be a view in greater detail. (Official recreations of the game work around the first issue by reducing the distances covered by objects on the roof to begin with.). (00:01:50)
Answer: When Ralph and the other bad guys enter Game central station. The camera pans out, to the lower left corner there is Maximus and in the upper left corner you can see the dinosaur. If you still can't see it, there is an intermission mode on the DVD that will allow Chris Hardwicke to explain this and other interesting things about the movie.
Rydersriot87