Continuity mistake: During the fight in the bathroom (just before Mater comes out of the stall), we see two grids on the floor. At one point, the orange car drives over one of the grids. But the grid disappears when Mater comes out the stall. (00:28:25)
Revealing mistake: When Mater and Holley are talking in the corridor, Mater's reflection is cast on the wall, but Holley's reflection isn't. (00:29:55)
Continuity mistake: When Miles Axlerod is arrested, the police car to the left is grey and the police car to the right is black. When Mater opens Miles Axlerod's hood, the black police car has turned grey. (01:31:32)
Continuity mistake: Tony Trihull appears when Finn McMissile begins chasing Professor Z. It also shows when Tony uses his magnet. When it is used, Finn's equipment are pulled by the magnet, which includes his bullets. Those bullets are black when all of them were going out. However, when they are pulled onto the magnet they are grey.
Plot hole: There is no reason for there to be sinks in the bathrooms. The cars may be able to use sinks just as they use toilets, but in the bathrooms they are too small and too inaccessible for any use.
Continuity mistake: When Holly and McMissle are convincing Mater to complete the mission, his door panels change between the shots facing the two and then facing Mater.
Continuity mistake: In the scene where Mater enters the terminal at the airport, a mark showing that his symbol was completely scraped off is visible on one of his sides, but when he goes through the gate, that mark is no longer there.
Continuity mistake: When the cars are zigzagging in the Tokyo track, there is a shot where three specialists are talking about McQueen and they show him on the track in split screens (air and ground shot). In the air shot, he has a red car behind and then a green one following. But in the ground shot, the red car is gone and the green is behind McQueen, even though you can see the red one in the air shot at the same time.
Factual error: In the credits, there is a paper revealing that Mater was knighted on Tuesday, July 15th, 2011. However, July 15th, 2011 was on a Friday, not a Tuesday.
Audio problem: When Mater wakes up from the dream in Big Bentley the time is 3 o'clock but the bell rings 5 times.
Continuity mistake: When Mater is going into the bathroom, all the stalls have red lights. In the next shot of the bathroom, all the lights are green except Mater's.
Other mistake: In London, the red telephone boxes seen are human-sized, so it is impossible for them to be big enough for the cars to even get into.
Continuity mistake: In the scene where Mater and Lightning enter Buckingham Palace, you can see a mountain as you look in the background. But when Finn and Holley enter while Lightning and Mater are moving closer to the Queen, the mountain has now become a tall building.
Continuity mistake: When the other tow truck asks how Holly Shiftwell's grandfather is, you can see that his Ivan symbol has a red background, and then a few minutes later you can see that Mater's Ivan symbol is white, and a few minutes later there is no background at all on Mater's symbol.
Other mistake: In the scene in the restaurant, where Lightning McQueen just hung up with Francesco, Sally says "You never bring him to any of your races" as a reference to Mater, even though Mater was at McQueen's last race in the original.
Suggested correction: McQueen didn't bring anyone to the first one; they all just showed up as the race started. The assumption is that since then, he hasn't invited Mater due to embarrassment of his public manner (judging by "this is exactly why I don't bring you along to these things").
