I wonder if it’s ever happened before that a movie contained a reference to another movie that had not been made yet.
We bought Monsters, Inc. on Saturday, and I watched it twice yesterday … once with my son, and again with my wife with the directors’ commentary turned on. The directors didn’t say anything about this, but it was obvious both times. Near the end, in the scene where Sulley is finally putting Boo back into her own room, she excitedly shows him a bunch of her toys. One of them is Jessie from Toy Story 2, and the very next one is the orange clownfish that appears in the teaser trailer for Finding Nemo, which won’t hit theaters ‘til early next year, at least.
I wonder if that detail was in the original MI prints that played in theaters nearly a year ago. Nobody would’ve noticed, then, because no information about Finding Nemo had yet been released. But they were probably far enough along with the concept work on FN that they had the little clownfish modeled.
It would be difficult, I suspect, to prove that this is the first “forward reference” in movie history. I strongly suspect that in the early days of Hollywood some props which were prominent parts of movies had previously appeared in insignificant roles in other movies. But this one is certainly intentional, and I was delighted when I saw it.