Deliberate mistake: Bowser has several teeth that appear and disappear throughout the movie. The best example of this is when Mario is trying to grab the Power Star. We see Bowser snarl at Mario before he picks him up. There is a gap between his two front teeth. However, when the scene cuts from Mario's horrified face to Bowser's face, there are now extra teeth inside that gap.

NeoMatrix

Visible crew/equipment: When Tom and Sonic pull over and the mini drone explodes, knocking Sonic unconscious, the camera pans away and you can see emergency vehicles blocking the road on the right of the screen, presumably closing down the road for filming. (00:59:55)

Revealing mistake: When Woody falls out of the closet wrapped in the string lights he hears Buzz's voice, and in the next shot as Woody sneaks up to Hannah's room we see Sid's open door and doorway, which looks perfectly normal. However, after Woody rescues Buzz from Hannah's tea party they both stop in the hallway, and there's another shot of Sid's open door and doorway, only this time it's not normal to say the least. Five of the six hasps, bolts, and locks that should be (and normally are) screwed into and attached to the inside of Sid's door (one hasp mechanism, third one down from the top, is attached to the door's frame) are now actually kind of floating there in mid-air right beside the doorway, as if there's an invisible door there. Weird that Pixar artists deliberately did this, but it's bizarrely funny to see.

Super Grover ★

Trivia: Harriet's chair in the spirit session is styled after the vehicles in the Haunted Mansion theme park ride.

Visible crew/equipment: A boom microphone is reflected in Luke's goggles when he says "Hey, what's the matter? You smell something?"

Continuity mistake: When Moana is throwing sticks into the ground, after she starts singing, look back at that spot and all the thrown sticks have disappeared.

Jon Sandys ★

Continuity mistake: When Sulley places the menu on the table he puts it face down (logo first), then when he lifts up the table, to quickly get Boo, the menu is face up. (00:26:05)

T1969

Continuity mistake: When Karl Urban is defending the Asgardians, the dust covers on his rifles vary between being open and closed several times. M16 dust covers are sprung loaded - they open on the first shot and have to be manually closed afterwards.

Question: When Tommy and Carrie are at the prom, does he start to like her for real, or is he just pretending to make Carrie feel better about herself?

Robin Hood: For my first order of business, I wish to appoint a new Sheriff of Rottingham. My friend, Achoo.
Achoo: All right.
Crowd: A black sheriff?
Blinkin: He's black?
Achoo: And why not? It worked in Blazing Saddles.

Trivia: Another Elf sighting is when Calvin and Charlie are first entering the dining room at Denny's - an Elf boy is putting on his coat to their left (our right). (00:08:50)