During the Quidditch match Harry's broomstick tries to shake him off, due to the spell. After Hermione tells Ron, "Leave it to me," in Harry's last close-up before he flips over, the seat that is attached to the broomstick, to make it more comfortable for Dan Radcliffe to sit on, is entirely visible. Glimpses of other seats can be had during the match as well.
For anyone who hasn't read the book: The inscription on top of the Mirror of Erised says "erised stra ehru oyt ube cafru oyt on wohsi". If you read the inscription backwards it says "I show not your face but your heart's desire".