The shot where all the orcs coming running into the elves and they spin their blades at the same? Shot in a carpark on the mountain because it had snowed the night before and would have ruined the scene.
More importantly it failed at, least for me, to establish what is and isn’t widely known about the world to the characters. Made me always wonder what took Gandalf so long to figure out that the ring Bilbo found was Sauron’s ring until I realized nobody is really meant to know it right away.
It would have been a lot more satisfying if the story was revealed slowly, with a major chunk of it discovered on screen through the conversation with Elrond.
Again, my opinion.
You are correct that the first rule of film making is show don't tell.