Continuity mistake: When Nora is explaining to her friends at lunch that she and Luther are skipping Christmas, her friend asks her "When do you leave?" without Nora ever mentioning that she and Luther were going on a cruise.
Revealing mistake: When the driver is taking Amanda to the airport at the end, all the dials on the car are at zero, so obviously the car is not moving at all.
Factual error: A toy modern four-door automobile and a clear plastic ball can be seen as the children play when the Burgermeister comes in on his wheelchair. Both unlikely for a story set (presumably) in the 1800's, at the latest.
Continuity mistake: After Sarah has called at Harry's office, Harry prepares to open his office door to see her out. The camera cuts back to Sarah for a moment, then back to the camera angle on Harry as she walks to the door. In that short space of time, the sliding cupboard doors have changed their configuration, and the blinds in the upper left of the frame have partially closed. (00:18:45)
Factual error: When hero boy and girl and Billy are on the runaway car at the north pole, they crash into the stopper at the end of the tracks. They are flung backwards when in reality, due to inertia, they should have been flung forward into the guard rail.
Visible crew/equipment: In the scene where Buddy and Michael are leaving the school, a crew member is visible in the bottom left of the shot. At first, he is just standing there, but he then tries to hide inside a doorway. (00:52:00)
Continuity mistake: The band-aid on Jill's doll disappears and reappears several times.
Continuity mistake: In the scene where Charlie and the snowman (his dad) are getting chased by the bullies, the sled gets split in half into two sled pieces. But you can clearly see that in some parts of this scene, Charlie is riding a real snowboard, and in others he is riding the half piece of sled.
Revealing mistake: During the ghost of Christmas present, Kermit is walking with tiny Tim on his shoulder and you can tell Kermit is walking on a spinning drum. Right before the camera pans away you can see Kermit's feet slide like he stopped walking but the road kept spinning. (00:55:00)
Factual error: When Howard is running after the bouncy ball he is on the second floor of the Mall of America, however, you see him run through the LEGO store which is located on the lowest floor of the Mall of America, which is impossible if he was on the second floor before.
Plot hole: In the scene when the robbers first enter the house, Kevin goes to hide in the shower. It looks like there is only one way out of the shower. How can Kevin possibly get out of the shower, let alone the bathroom, without getting wet after he turns it on?
Other mistake: Grand-Santa has made 70 missions, and Santa (Malcolm) has just completed his 70th mission, totaling 140 years. Yet Grand-Santa is only 136 years old.
Suggested correction: Grandsanta's portrait is shown in the halls of the North Pole with the dates 1902-1941 (with Malcom having done 71 missions from 1941). Therefore he did 39 missions. That makes for a total of 109 years, meaning he was 27 when he took over from his own father.
Continuity mistake: In the scene where Santa is getting married, just after they kiss and Santa looks like Santa again, you can see in the bottom left hand corner Bernard and Curtis giving each other the thumbs up. In the very next shot, it repeats them doing this again only in a close up. (02:33:00)
Character mistake: When Mr Maddens is talking to the critic at the Mayor's reception, he calls him Alan. The character is actually called Patrick Burns, Alan is the actor's name.
Continuity mistake: When Lucy and Jack are walking along the river, a long shot shows them approaching a lamppost with a kissing couple. In the next shot, they pass the lamppost but there is no one there. They finally pass the couple at the next lamppost. (00:46:55)
Suggested correction: The couple is there. They are walking one lamppost before the couple in the long shot, and they are walking very slowly. In the close-up, it shows them just passing the lamppost before the couple. When they do pass the next lamppost, the couple is there as they were in the long shot.
Continuity mistake: At the end when the sled full of Christmas stuff is on the mountaintop, it starts sliding off the edge. It's going fast enough that it should be long gone by the time the Grinch reaches it, but when he does it's still right near the top of the mountain.
Continuity mistake: When Cornelia leaves some food and a can of soda out for Joe, the label says "Coke." In the next shot, when Joe goes to get the meal, the label on the can is "Coca-Cola."
Factual error: A very common error in First World War films. British soldiers were not permitted to shave their upper lips until 1916 - in 1914 almost all (unless physically unable to grow them) would have had moustaches.
Continuity mistake: The first movie shows Santa slipping on the roof and kicking up a white snow blanket as he falls. The flashback in the third movie does not show the blanket being kicked up as Santa slips.