Santa Clause II, The - The Disappearing Magnifying Glass
When the Santa Clause is sitting at his desk, arguing with his elf... whats his name... he is holding a magnifying glass. moments later, the shot is moved to the elf, and the a split second later back to Santa, who is no longer holding the magnifying glass.
"The Santa Clause" is not the name of the character, it is the name of the movie (series). The character's name/title is Santa Claus. "Clause" refers to a term of a contract and is used as a pun for the name "Claus."
(This does not affect whether the slip-up is genuine or not. :-) )