My humor is pretty rotten so I always found Scary Movie 3 the funniest shit ever since it came out. I was never, however, a big rap fan, so 8 Mile never peaked my interest when I was younger.
Decided to check out the movie a few days ago and you can imagine my surprise when I noticed the final rap battle took place in a set that looked exactly like the one from SM3's rap sequence.
Then my dumbass self realized the scene I had watched nearly a hundred times was parodying Eminem's film. Trippy shit.
TLDR: took me years to notice Scary Movie parodied 8 Mile.