When Wreck-It Ralph realizes he is in the Sugar Rush game he says, "This is the candy go-cart game over by the Wak-A-Mole." However, at the beginning of the movie, as the camera rolls away from the Fix-It Felix Jr. cabinet, the game next to Sugar Rush says Wak-A-Troll.
On The Racer-board near the end of the film when the random roster race begins the Racer-board shows 16 racers but number 16 for Vanellope is flashing because she has not arrived but when they go to start the race there are 3 lines of 5 Kart places and 14 of them have racers and the 1 flashing is for Vanellope so that adds up to 15 but on the Racer-board it added up to 16 that means there is 1 racer missing before Vanellope even arrived.
During the race sign up scene, when each racer is throwing their coin into the gold cup as the entry fee, the announcer says Snowanna Rainbeau, and you can see a blue haired pig-tailed character just behind Rancis Fluggerbutter. This character is Citrusella Flugpucker, the 6th listed racer on the board, but she is announced as Jubileena Bing-Bing, who is listed 13th on the board. Jubileena Bing-Bing is the red pig-tailed racer, not the blue.
When the Sugar Rush racers are throwing in their gold coins to enter the Random Roster Race, the announcer can be heard reading the name "Adorabeezle Winterpop" third, after Taffyta Muttonfudge, and "Crumbelina Di Caramello" fifth, after Gloyd Orangeboar. But the next time the roster board is shown, Crumbelina's name is printed on line 3, while Adorabeezle's name is on line 5. The board's order may be considered the correct one, as not only does the same order appear on it again as the race commences, but Crumbelina can be seen lined up right behind Taffyta just before they begin to toss their coins to the pot.
Vanellope's Kart has a strawberry on the front right wheel and a lemon on the front left; the rear wheels are just cookies. Best view of the lemon occurs when King Candy flips Vanellope's kart in the tunnel. When Vanellope crashes just before the finish line, the front wheels have switched sides. The lemon(now right wheel) departs during the crash and the strawberry is shown as the front left wheel.
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.
When Vanellope crashes just before the finish line, the color pattern of her kart's six straw exhausts are different before and after the arrival of Felix and Ralph. The "after" color pattern is the correct pattern that matches the rest of the movie. The "before" color pattern seems to have the left and right exhausts swapped.
When Ralph doesn't appear in his game, Felix climbs off the side of the apartment building and exits the screen. In the next shot, he is just seen exiting the light source, indicating that he has left the screen again.
Ralph's first game in Hero's Duty happens just after the arcade opens. By the time Ralph gets to the top of the tower (which is implied to be before the next game starts by the "Quarter Alert" heard at the end of the first game), the arcade has closed.
When King Candy visits Ralph to tell him to stop Vanellope from racing and gives him his Hero Medal, Ralph stuffs it in his overalls. The blue ribbon of the medal is not visible on a number of shots until Vanellope spots it and then the blue ribbon is visible.
When Ralph smashes the cake, Mary is seen stood 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.
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.
When Ralph approaches the candy tree that his medal is stuck in, the camera shows a rising shot of the whole tree from bottom to top, then a shot looking down the tree from near the top, but neither Vanellope nor any double stripe branches can be seen in these shots, even though they both appear seconds later when Ralph climbs the tree.
At the start of the movie, Fix It Felix Jr is at the back of the arcade and facing the door. Sugar Rush is two or three machines down. However, at the the end of the movie, Fix It Felix Jr is facing Sugar Rush, they are opposite each other.
In the opening sequence, when Ralph is explaining his life to the viewer, arcade closes and the camera travels through the Fix-It Felix console's screen. Being that nobody is playing the game, the title can be seen on the screen from outside, and, in a brief shot, within the game world, too.
Later in the movie, when Ralph returns to the game and throws his medal at the back of the screen, that logo cannot be seen.
When Ralph gets trapped in the cupcake and is at King Candy's castle talking to him, the Oreos are behind King Candy and pointing spears at Ralph. However, when the shot switches to Ralph and back to King Candy, the Oreos aren't pointing their spears at Ralph but just holding them. When King Candy dismisses the Oreos, they pull back their spears as if they had just finished pointing them and walk away.
When King Candy enters the program he goes out the direction of Vanellope's code box. In Sour Bill's flashback however, King Candy's rope is to the left while he's pushing Vanellope's code box to the right.
As Ralph is headed for his game after the Bad-anon meeting at Pac-Man's, he's walking through Game Central Station where Dig Dug sees him and burrows through the ground in fear. He can then be seen moments later near the informational kiosk with Sonic the Hedgehog.
Ralph says he gets a perfect view of the game Sugar Rush when he is lifted at the top of the building, as if he cannot see it from a lower position. In a previous scene, though, he can perfectly see the game from a balcony. However, Ralph would be unable to watch Vanellope race from the balcony during in-game hours, like she had wanted, and being lifted by the Nicelanders is the only way to for him to view Sugar Rush if there is someone playing his game.
When Ralph emerges from the chocolate milk after avoiding the police and devil dogs he is completely dry. He should be completely soaked. This is, however, assuming that Sugar Rush would have a realistic physics engine, or that Ralph, being a character from a different game, would be affected by it; Vanellope is pushed into the mud later on yet also remains completely dry and clean.
Vanellope uses a medal that Ralph took from Hero's Duty to pay her fees and enter the Random Roster Race, after which it is shown dissolving into the game's code until retrieved by King Candy later on. Unless the coding for the medal in Hero's Duty happened to be identical to that of the gold coins that are typically used in Sugar Rush - which is unlikely - the game should have crashed upon detecting the foreign code within its system, rather than accepting it as payment as was shown.
The goof items below may give away important plot points.
When Ralph looks down on the entrance of Sugar Rush after being lifted by King Candy, you can see the path is empty between Calhoun, Felix, Vanellope and the cy-bugs. 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.
When Calhoun tells everyone to go to Game Central Station, the sign at the finish line reads 'FINISH'. A few seconds later, when Ralph looks up to a board with a map of the racetrack, we see the sign on the finish line still reads 'START', which flashes for a moment before reading 'FINISH'. He turns to the sign again, which has just started reading 'FINISH'.
When Ralph asks Sour Bill for information about Vanellope, Sour Bill tells Ralph that King Candy tried to delete her from the code and locked up the memories of everyone in the game. If that's true then Sour Bill shouldn't be able to remember King Candy's attempt at deleting Vanellope.