Actually: It’s both “Mirror, mirror, on the wall…” AND “Magic mirror, on the wall..”
In the 1937 Disney classic, Snow White and the Seven Dwarfs the Evil Queen utters the famous line “Magic mirror, on the wall – who is the fairest one of all?”.
It has not been changed or edited since its original release. There is no credible evidence to support that it has. The mirror’s persona in the Disney adaption is named, “Slave in the Magic Mirror”, hence why the Evil Queen refers to it as the “magic mirror”.