(at around 9 mins) In the first film, Mr. Litwak's name is listed on his name tag as Stan. In this film, it's listed as Del.
(at around 6 mins) In Wreck-It Ralph (2012), the Sugar Rush game is shown being a double console game with two steering wheels and two seats. In this movie the game is a completely different console: standing version with only one steering wheel. There is no mention of this console change, of the game being unplugged and replaced. This was an obvious change for the main plot of a broken steering wheel, but inconsistent with the original movie and unexplained.
(at around 1h 30 mins) When Ralph rips his Snow White dress, it shows his bare midriff, yet he was still wearing his own clothes when he landed in it.
The leaderboard somehow still shows 16 racers even though the 16th racer, King Candy/Turbo, was destroyed in the previous film.
(at around 10 mins) Surge Protector says at one point "I haven't seen this many gameless characters since Space Invaders went down". However, at the very beginning of the movie the game Space Invaders (1978) is shown right next to Fix-It Felix Jr. game and it's on same as all the other games.
(at around 56 mins) The flannel shirt of Merida's comfy outfit is the same color as her usual dress rather than the official DunBroch tartan pattern Disney/Pixar created in 2011 and registered with the Scottish Register of Tartans in 2012.
(at around 31 mins) It's extremely unlikely any virtual video game car would ever sell for 40,000 dollars. That's way more that what you could buy a real life car for.
(at around 23 mins) When Vanellope first arrives in the internet and searches KnowsMore for the steering wheel he returns a single search result at eBay. When she clicks the link, it takes her to the main landing page at eBay.com. She is then forced to try to find the steering wheel among the other auctions. In reality, clicking that link would have taken her directly to that auction. However, we don't know if KnowsMore provides deep links or just links to the front page.
(at around 2 mins) Vanellope tells Ralph they shouldn't play Tron (1982) because it has a "virus". Coin-operated games don't get viruses because they aren't connected to the internet. They have "bugs" in the software. This mistake was likely deliberate to create continuity in terminology and foreshadow the effects a virus has on a game.
(at around 25 mins) Since Ralph and Vanellope are clearly regarded as two separate entities bidding for the same item (the steering wheel), it is correct that Ralph as the last bidder is charged the full $27,001 amount. If the auctioneer had seen them as a single entity, they would only have to pay the first higher bid of $1,000. But then he would not have accepted the $15,000 or higher amounts, since you cannot bid against yourself.
(at around 2 mins) Sonic the Hedgehog once said that if a character dies in a different game that they wouldn't be able to regenerate, and yet when Ralph and Vanellope were in Tron (1982) they froze as if they were about to die. However, the crash of their light cycles in the game did not technically kill them. They were merely frame-frozen in mid-air due to the virus affecting that part of the game.
(at around 54 mins) In the Princess room, Rapunzel's hair is blonde and long, as in the opening of Tangled (2010). However, at the end of Tangled, Rapunzel's hair was cut, making her hair color brown and the shape of brunette. The versions of the Princesses that appear in this film are meant to be avatars of the characters as they appear in promotional material, not the 'actual' characters.
After the virus makes copies of Ralph, it's not accounted for anymore. By its programming, it should continue to look for more insecurities and replicate it in the internet until someone or something stopped it, which is not shown in the movie.
(at around 1h 30 mins) If Spamley's truck couldn't withstand the force of Ralph falling onto it from such a great height then Snow White's dress would've had no chance.
(at around 38 mins) If Vanellope can 'glitch' through the fire, bringing herself with the whole car and Ralph crossing it safely, it should be possible that she could bring the car further outside the game and not be stopped by Shank.
(at around 3 mins) In Wreck-It Ralph (2012), where Ralph meets Vanellope, it's the 30th anniversary of the Fix-It Felix Jr. arcade game. But in this film (which takes place 6 years later), Ralph says that he met her after he'd been around for 27 years.
(at around 1h 18 mins) During Vanellope's argument with Ralph, she says "I'm one of 16 racers" when there are actually 15.