I think this was an American kids/YA television movie from some time in the 1990s, but I’m not 100% sure. I don’t remember the plot or specific context.
Anyway, there’s a smart kid whose dad has a prized letter supposedly written by Abraham Lincoln. At some point, the kid tells dad the letter is fake; dad doesn’t believe him. Dad gets mad because (I think) the letter gets damaged or defaced or something? Later, at a party or gathering of some kind, one of dad’s friends/colleagues looks at the letter and correctly identifies it as fake because Lincoln never stayed at the hotel the stationery was from, thus proving the kid right.
I vaguely remember some of the dialogue, where the guy who inspects the fake letter says something like, “Lincoln never stayed at [name of hotel]. This letter is a forgery.”
I do not know why this popped into my head, but I cannot seem to remember the movie for the life of me, and it’s very frustrating. If anyone else remembers this or can find it, I would be eternally grateful.