Other mistake: In the end credits, Santa's name in the song title "Santa Claus is Comin' to Town" is misspelled as "Clause."
Other mistake: When the Grinch rides his sleigh back to Whoville and returns everything, as the narrator says, "He brought back their pantookas," a pink ornament lands on the Christmas tree, then changes to yellow mid-shot.
Continuity mistake: In the scene where Bill's old boss comes back to see him notice when Bill shoots him and takes the drink. All of the drink comes out of his chest because of the bullet holes. Well notice his shirt is all wet, then in the next scene when he takes off his hat his chest is all dry.
Continuity mistake: The view out the back of the barn door when it's first revealed does not match the same view, just minutes later, in the final shot of the film. (01:55:43 - 01:59:12)
Visible crew/equipment: During the final song, while they're all at the dinner table, there's a crouching puppeteer with a blonde ponytail next to the rats.
Continuity mistake: When Lucy is in the Callaghan's house at Christmas at the very end of the scene it shows her stocking and her name on it is in white letters. However, in the scene where Mary comes in and tells the family that Lucy is pregnant, the camera pans to Jack who is standing right beside Lucy's stocking, only this time her name is in black letters.
Continuity mistake: During the second round of drinks, the amount of ice left in the frozen daiquiri changes depending on the camera angle. It's poofy and opaque in the side view, and deflated and almost fully transparent in the tighter close-up on Shirley MacLaine, with an intermediate angle and state. (00:38:10)