12 Biggest Retcons In Harry Potter Movies

5. Incantations For Spells

The Harry Potter book series sees the evolution of spells to become wordless, so there's some precedent for changes to the way they're shown. But one change from the first film onwards is less easy to forgive.

In the first film, as Sheamus comically shows, spells can be done using old school incantations that could have been ripped from a cliched witch's handbook. In attempting to show off his new magical skills, he says:

"Eye of rabbit, harp string hum, turn this water into rum."

Inevitably, because it's Sheamus, it doesn't work, but the fact that it backfires suggests that it was his incompetence rather than the spell that's a problem. From there on, nobody even mentions that sort of incantation - either one or two word magical slogans are shouted or the caster says nothing at all.

There are also two other changes to spells: in the Prisoner of Azkaban spells make a whistling noise (but it's undone again after that film), and the Expelliarmus charm changes from its first appearance. Initially, it's joined by a bright, golden beam but from The Prisoner Of Azkaban onwards, that was replaced by a spark.