Movie Mistakes #1: Sorcerer’s Stone
In the flashback, when Voldemort kills Harry’s parents, baby Harry can sit up and has hair, yet the baby Dumbledore places on the Dursleys’ doorstep is much younger.
When Harry receives his first letter, Dudley snatches it from him before he has a chance to open it. Dudley then gives it to Uncle Vernon, who says, “Who’d be writing to you?” Watch Dudley carefully - he’s mouthing the line.
After Hagrid gives Dudley a tail, watch him in the background while Dudley runs around. You can see it’s not Robbie Coltrane, but a double with a beard.
Awesome! Wish I had been paying close enough attention during our HP-fest to have spotted these myself!