Harry Potter: 10 Majorly Dumb Plot Holes You Never Noticed
2. Expelliarmus Is The Deux Ex Machina Spell
What caused it: Initially the films using the existing mythos to create new things, but ultimately the story developments defined by the book requiring it.
When turning what was a children's book into an action adventure, some changes clearly need to be made. Essential for Harry Potter was having an easy, go-to incantation that could be used a generic attack spell. The games had the right idea, inventing new spell Flippendo (only works properly if you really shout it), but the films struggled a bit.
The books had very specific spells, but also had the time to explain and be creative with them, something even the longest film didn't have. And thus expelliarmus, in the novels the disarming spell, became the general attack spell. An easy switch that annoyed fans, but didn't damage the series, right?
Wrong. When David Yates took over he reattributed many of the spells; stupify became the normal attack one and expelliarmus reverted to being the disarming spell. Coming after four films of the contrary its a rather major plot hole, but one that needed to be done to plug a much bigger potential problem, which forms the basis of the final error...