A commercial for Energizer batteries that tied in with the original movie has Lightning McQueen run down near a billboard with the Energizer Bunny next to his slogan, "Keep Going" on it. Mater catches up to Lightning and advises him to be in it for the long haul, citing the Energizer Bunny as someone who has the right idea before he tows Lightning away.
Finding Nemo: Luigi makes a very brief cameo during the scene right before the credits, where we see that the Tank Gang has managed to escape the tank.
The Incredibles: During the battle with the Omnidroid 10, a blue Hudson Hornet resembling Doc Hudson can be seen parked in the background.
A toy resembling Lightning McQueen is seen in the background on the floor of Sunnyside.
A toy tractor, like the one seen in Cars, can also be seen in Sunnyside.
One little boy is seen wearing a shirt with a #95 and a lightning bolt on it, both of which are what Lightning McQueen has painted on his sides.
In the scene where Buzz sees Lotso's minions gambling inside the vending machine, "ReVolting" batteries are one of the things placed on the See N' Say roulette, "ReVolting" being the brand of car battery that Davey Apex beared the sponsor of.
Rapper Yung Nugget's Signature Song is titled "Lightning MacQueen." In the lyrics, the rapper compares himself to McQueen and says "ka-chow" several times. The art for the song depicts him escaping a line of police cars by riding Lightning McQueen.
Schaffrillas Productions: A (since unlisted and now somewhat hard to find) video titled "Will They Be in Smash?" discusses how Lightning would work as a fighter in Super Smash Bros.... before deciding that he wouldn't work because, as a racecar, he would have a very limited moveset - and besides, how would he hold items?
In "Cody's Revenge!", after breaking a table with Bowser's clown car in a previous episode, "Bowser Junior's Clown Car", Bowser threatens to send Junior to military school. Sergeant Brooklyn T. Guy tells Junior that at military school, he's going to make him watch Big Hero 6. Junior is horrified, claiming that "Big Hero 6is the worst animated movie sinceCars 2".
In "Chef Pee Pee's Date!", Chef Pee Pee and Lola watch a preview for Cars 4 in the movie theater. In the preview, a drunk Lightning McQueen crashes into a lamp post.
The couch gag used in the episode "Puffless", has the family resemble characters from the movie. When they sit on the couch, Maggie appears as a monster truck and crushes the rest of them.