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: In the scene where Ralph smashes the cake, Mary is standing behind Gene. She's not holding anything during the smashing, but as Ralph begins to leave the party the camera shows Mary holding onto the cake figurines which would have been smashed previously. (00:13:40 - 00:14:15)
Continuity mistake: It's established that in the candy cane trees, the double striped branches 'break'. When grabbed, they make a loud noise and flash for a moment, before just vanishing. When Ralph and Vanellope are racing to the Hero Metal at the top of a tree, Ralph hits several of these branches. Each time, the branch only lasts about a second or two after he touches it before vanishing. However, he then falls from the tree and lands on a branch that is double striped and hangs from it. While doing so, he proceeds to have a full on conversation with Vanellope, for a relatively long time. Yet the branch does not vanish till after she walks away, despite previous ones having only a second or two of time before vanishing. (00:30:35)
Continuity mistake: When Deanna begins to pull Felix onto the dance floor, she is wearing a shiny dress imprinted with leaves and flowers. When they take their places in the next shot, Deanna is suddenly in a plain pink dress, with no imprints. Then, although she remains on the dance floor for the entire shot, when Gene answers Felix in the very next shot, Deanna is suddenly with Gene by the door, and she's back in the dress with the shiny imprints for the rest of the scene. (00:09:55)
Continuity mistake: When Felix calls Calhoun a "dynamite gal" she has a flashback of her former fiance calling her a dynamite gal. The last time he called her a dynamite gal, it was at the wedding. He only manages to say "dynamite" before the cy-bug bursts through the window and he gets eaten by the cy-bug. However, during the first flashback of Calhoun's former fiance before she and Felix enter Sugar Rush, it shows the former fiance getting eaten by the cy-bug at the wedding, but he didn't say "dynamite gal" before he was eaten. Also in the first flashback, their arms are by their side. But in the second flashback, their arms are interlocked with each other. (00:32:20 - 01:01:15)
Continuity mistake: When Ralph looks down on the entrance of Sugar Rush after being lifted by King Candy, you can see the path is empty between the three characters and the cybugs. But when Ralph frees himself from King Candy's grip and Vanellope starts glitching towards Ralph, you can see Calhoun's discarded weapon lying on the ground. Something so distinctly black would stand out on the rainbow bridge from a distance. (01:24:55)
Continuity mistake: During the Hero's Duty scene we see Calhoun from the player's perspective. When Calhoun says "The kitten whispers and tickle fights stop now" the players ammo shows 3/15, showing a full clip is 15 shots. We then cut to Ralph running inside and then back to the player's view and the ammo is now 5/15. The player can't have reloaded the gun in that time as we saw the player when we cut to Ralph.
Continuity mistake: When Calhoun and Felix are in Game Central Station getting ready to enter Sugar Rush, one of the portals behind them is displaying the words "Now playing Burger Time," meaning the game is in progress. But shortly afterwards you can see Peter Pepper, the main character from that game, serving what looks like a pie to the characters from Q-bert. (00:31:20 - 00:31:55)
Continuity mistake: In the very beginning, when Ralph is explaining to the bad guys how Fix-it-Felix Jr. works, and how he would rather be a good guy, it shows Ralph and Felix playing their game. When Ralph comes out and starts wrecking things, he puts a hole in the window to the right of the door. When Felix begins to fix things, the window now has two holes.
Continuity mistake: When Ralph makes the track inside Vanellope's hideout, the road is completely plain, with no obstacles. Later on in the scene, Ralph is guiding Vanellope around some sort of obstacles, which is a big group of spikes coming out of the ground. When Vanellope begins to drive on her own, the obstacles are gone.