For me it was some of the battle shots, particularly one of a Volge pulling one of the defenders off the cliff and dropping him. In that and some of the other falling shots, the way the bodies moved just didn't fit how gravity and inertia should work. That was the deftest piece of exposition in the pilot -- encapsulating their whole relationship without needing to give a word of backstory. A perfect "show, don't tell" scene. And note that they did, in fact, not shoot the deputy.