This movie is just one long love-letter to retro and arcade gaming.
Several sound effects:
When Felix lifts the magic hammer, a version of the familiar Mario coin sound effect is heard.
Another audio Shout Out that's easier to miss; the sound effect that plays when Felix gets a pie is the same sound effect used when Mega Man gets an enemy ability from Mega Man 3 onwards.
At one point when Tamora Calhoun draws her gun, it makes the charging sound effect that X's buster makes when he charges it from Mega Man X4 onward.
Yet another nostalgic sound can be caught in the second trailer where Felix, trying to escape from the jail by hitting the window bars (but fixing them unintentionally instead): It's the Start Up-sound from Gradius!
When Ralph is searching through a box and finds an exclamation point, the sound that accompanies it is the "alerted" sound effect from Metal Gear Solid.
Tamora Jean Calhoun shares her last name with Mackenzie Calhoun, as well as with Barney Calhoun from Half-Life. Her first name may be a reference to Tamora Pierce, an author known for writing strong female characters. Jean may be a reference to Billie Jean King, a former World No. 1 tennis player who won the famous Battle of the Sexes.
Ralph punching out one of the windows in the in-universe version of Fix-It Felix Jr. looks like something out of Rampage.
Ralph accidentally stepping on a bug egg, causing it to hatch, attempting to escape in a shuttle, having it attach to his face and then escape the pod to go propagate before finally assaulting the new world in which it finds itself seems eerily similar to the Alien franchise. The Cy-Bug eggs also glow from within with the same sickly glow as Xenomorph eggs.
And in a blink-and-you'll-miss-it shout-out to the "They're in the room!" scene from Aliens, Calhoun's tracker shows her completely surrounded by Cy-Bugs while standing in an empty field in Sugar Rush. Then the ground caves in and she falls into their nest. It's also simultaneously a shout-out to Alien, as Calhoun dangling from a rappelling line while hanging above a large chamber filled with alien eggs is like a scene with John Hurt's character in the alien ship.
Calhoun's rifle looks not unlike the pulse rifles from Aliens, too.
The TurboTime arcade cabinet is reminiscent of the Rally-X cabinet.
Of the same flavour, we have a racer called Di Caramello, which, if you pronounce "Caramel" as "Carmel" you get something that sounds oddly like DiCaprio with a candy twist, which may or may not have been intentional.
The scene where the other racers destroy Vanellope's kart is played like the stepsisters destroying the dress in Cinderella.
There's also a non-video game shout out as after Ralph chases off the racers of Sugar Rush who were destroying Vanellope's kart, he refers to them as "the Children of the Candy Corn".
When King Candy digs around in the game's code, he says "End of the Line!", an almost word-for-word quote of MCP.
When Ralph picks up Sour Bill and forces him to tell him the truth about Vanellope, Ralph licks Sour Bill. Then Ralph smiles and says, "I wonder how many licks it'll take to get to your center?". The Tootsie Pop slogan has never sounded so badass.
The track inside the mountain where Ralph teaches Vanellope how to drive is like the Big Donut multiplayer stage from Mario Kart 64, being a circular track inside a volcano.
In the scene where Vanellope and King Candy are racing on the Rainbow Road-esque track, King Candy jumps onto the road in his cart... just like the famous cheat from the Mario Kart 64 version where if you jump off at a certain point in Rainbow Road, you can land on a lower portion of the track ahead of other racers.
Also, the items come in boxes marked with question marks, and a homing weapon is red-colored and comes in a bundle of three, much like the red shells.
The opening segment of the final race also (in terms of the camera angle) mirrors the introductory cinematic of another Mascot Kart Racer...
Also a shout out to Acceleracers, the part where Vanellope drives through a wall is reminiscent of how one gets to Tesla's Acceledrome.
The part where Ralph and Vanellope create a kart is done by series of minigames using cooking ingredients and tools, very reminiscent of Cooking Mama games.
The "power cards" Litwak's Arcade uses are similar to the real-life arcade chain of Dave and Buster's, which uses electronic cards instead of coins (though Litwak's Arcade utilizes both coins and power cards).
The drunk Hero's Duty Marine that Ralph meets at Tapper's just keeps walking pressed up against the wall, as if locked in a walking animation, in a manner familiar to gamers who've had experiences with AI bugs.
Many of the guns seen in Hero's Duty start out in a compact, storage form and then expand into their fully functional forms when drawn, possibly a reference to the weapons in Mass Effect.
The other kids wrecking Vanellope's car bears some semblance to the SUV-wrecking bonus stage from the Street Fighter games. Minty Zaki even does a Ground Pound.
The SUV wrecking stage is shown in the credits with Ryu, Ralph, and Vanellope doing the beating. This is followed by Ralph fighting Blanka.
Even the soundtrack joins the referential fun: the name for the track playing during King Candy's introductory scene? Royal Raceway!
It's likely that a lot of people nickname this movie "TRONsters Inc". In particular, the Beacon in Hero's Duty bears a strong visual resemblance to the Portal in TRON: Legacy, and the panels swirling around the Hero's Duty medal resemble the MCP's shields from the original Tron. The reset of Sugar Rush when Vanellope crosses the finish line and becomes Princess Vanellope is very reminiscent of the reset of the system at the end of Tron.
The first stage (save the good ingredients, junk the bad ones) of the "bake-a-cart" mini-game strongly resembles the ZX Spectrum game Cookie.
During Ralph's Imagine Spot about returning with the medal, the 8-bit tears Gene cries are similar to those cried by the cops in an obscure coin-op, Lock and Chase, both visually and audibly.
Felix, being the nice, innocent good guy that he is, tries to refrain from using popular obscenities, replacement obscenities, or minor words like "My God!" for frustration or astonishment Instead, he uses many... unusual replacements in his vocabulary, such as "My Land!" for "My God!"
A story centered around a team of four protagonists, who all ultimately come together under the sake of the team's little girl, save the world from an evil king who turns out to be a threat even greater than they think, and the girl takes back her rightful place as her world's true ruler?
In addition to No Celebrities Were Harmed, Alan Tudyk's performance as King Candy is a superb impression of actor Ed Wynn's distinct voice and vocal mannerisms, while Candy's character design is a direct Shout-Out to Wynn's character of the Hatter.
When Ralph starts to explain why Vanellope can't race, he says that he's been thinking. Vanellope replies, "That's Dangerous," much like Lefou's reply to Gaston saying the same thing in Beauty and the Beast.
A non-gaming example, the rock guitar rendition of the Wedding March sounds a lot like the Queen rendition of same from the Flash Gordon movie.
Another non-gaming example: the sound effect Calhoun's gun makes when it fires is the same sound as the phased-plasma pulse rifles in the future war of the Terminator movies. And her pistol is modeled after the Auto-9 used by RoboCop, despite being a laser weapon. Watch closely during the scene where she reloads it, which is like a scene in that same movie.
When Vanellope is learning to drive, she keeps running into Ralph, or causing damage that causes him to get hit anyway. The sequence is like a Wile E. Coyote and the Road Runner cartoon where, no matter where the Coyote stands or hides when he triggers a catapult, it squashes him.