Revealing mistake: The wires holding up Jacob Marley's floating lock box and chains are visible. (00:32:10)
Revealing mistake: In the big scene at the children's show when David and Natalie are revealed kissing behind the curtain, many members of the audience are shown snapping picture after picture. One of the guys who is snapping away very rapidly has a "throw-away" one-time use camera. All one-time use cameras have wind wheels, meaning you can't take photos that quickly. (01:54:15)
Revealing mistake: In the scene at which Dan Aykroyd first joins his employers at the gentleman's club, Don Ameche is shown mirror image when he adds his signature. It happens again at the very end, during Ameche's credit, one of these flipped shots from this scene is repeated. (00:12:00)
Revealing mistake: When Chris and Jamie are on their day date in the diner, Jamie has a grilled cheese sandwich with ranch on the side. However it is obvious that the bowl of ranch is empty. (00:33:10)
Revealing mistake: When the Grinch is cutting Max's antler, the cut lines appear on the prongs before he actually starts to cut.
Revealing mistake: In the flood scene, you can see six inch boards on all the doorways keeping the water from spilling into adjacent rooms. (00:28:23)
Revealing mistake: One of the reindeer's "power-up" lights turns on before its name is called.
Revealing mistake: You can see Buddy and Finch's stunt doubles in the ice skating scene. And when they are showing a close up of them you can tell that they are not really ice skating, but just doing the ice skating movement.
Revealing mistake: In the scene where Kim comes home early from the camping trip, Edward is startled and begins stabbing the water bed, thus causing it to spring many leaks. If you actually look at the bed, it isn't jiggling like a water bed should and the water is just spraying out even in places he isn't stabbing.
Revealing mistake: In the beginning when Nick gets a present from Fred you see that the background is fake.
Revealing mistake: When Neil is teaching Yoga exercises to the elves a first close up shot of one of the elves (the Asian looking one) shows he doesn't have pointed ears like the rest in the group.
Revealing mistake: The stick used to make Jack's dog levitate is sometimes visible, for example when Jack is alone on the mountain.
Revealing mistake: When George is on the bridge and says "I wanna live again", and Burt drives up, in the shot where George hugs Burt, then Burt pats him on the back, you can see Burt's handprint in the fake snow that was used (a mixture of foamite soap and water) on the back of George's coat. (02:02:35)
Revealing mistake: When the cab skids off the road and down the hill you can see that it never actually hits the tree - it is yanked back with about a decimeter left to go before it would hit.
Revealing mistake: Toward the end, after Ricky decapitates the old Mother Superior, a young nun assumes she is alive and taps her shoulder. Mother Superior's head falls off and to the floor. There is no blood whatsoever. The old woman had just been decapitated moments earlier, and there isn't even a drop of blood, not even on the white part of her nun outfit at the neck.
Revealing mistake: Certain parts of this film were made during the spring months, not winter. In the background of the high up shots during the parade, leaves can be seen on trees (in the distance). Also, the grass is surprisingly very green, in several locations.
Revealing mistake: You can see Hero Boy putting the ticket in his pocket after getting it punched the second time, before finding his seat on the return journey. However, the ticket slowly evaporates in the air as he is about to put it into the pocket. His hand thus enters the pocket ticket-less.
Revealing mistake: When Krampus walks toward Max after he yells at him to give him his family back, wires are controlling Krampus' arm. (01:24:30)
Revealing mistake: When Santa starts reciting the long list of things the little boy wants for Christmas, you can see the boy's eyes reading Santa's lines off-camera.
Revealing mistake: One of the accountants' computers has no power cord attached to it.