In June 2017, Entertainment Weekly reported that during the voice-actor recording process for Les Bagnoles (2006), director John Lasseter spent a lot of time in the recording booth with Paul Newman, who often regaled him with stories about his life and his many years as a race car driver. Lasseter said, "In a way, he mentored me in racing, because car racing was his true life's passion, and I made sure that whenever he came into the recording booth, we were recording everything. In-between takes, he would tell me stories about great races, and you could hear the passion in his voice." Those recordings made it possible for Doc Hudson to reappear in this movie, released over eight years after Newman's death. Lasseter explained, "as we started Cars 3, we went back to every recording we did on Cars 1 and catalogued and listened to it all, and ended up with a lot of material that we could use; lines that were cut from the original film and never used, as well as some of those pieces from in-between takes."
When Cruz Ramirez (Cristela Alonzo) is training the new millennial cars on the treadmills, she plays music for one car to remind him of home, and shows him a scene on the television. The scene is from Coco (2017), and the car comes from Santa Cecilia, where Coco took place.
Tom Magliozzi died in 2014. Instead of hiring a sound-alike, filmmakers reviewed old transcripts from Car Talk to find lines that would serve Rusty. Car Talk was a weekly NPR radio show hosted by Tom and Ray Magliozzi, where they were known as "Click and Clack, the Tappet Brothers." "Don't drive like my brother" was their catchphrase at the end of the show.
Cal Weathers, the old-generation 42 Dinoco car, is voiced by Kyle Petty. Kyle is the son of Richard Petty, who voiced "The King" 43 Dinoco car. Kyle raced many years in NASCAR, but had less success when compared to his father's seven championships and two hundred race wins. The running gag in the movie where Cal overhears his replacement attempts makes more sense with this background information.
The Pizza Planet truck appears during the Figure 8-demolition race.
Lewis Hamilton: the voice of Hamilton, Cruz Ramirez's on-board computer. He previously voiced himself as WGP racer "Lewis Hamilton" in Les Bagnoles 2 (2011).