Star Wars Episode 4: A New Hope - Wrong Character
At the end when Luke fires his blaster into the Death Star's only vulnerable spot, it's not Mark Hamill. I don't know why, but they accidentally use Harrison Ford in that scene. You would think that they would've known we'd notice. Also, C3-PO is riding on the back of the craft replacing R2-D2. And when the Death Star blows up, it's really a peach. I'm surprised nobody has posted this yet.