During the night battle with Malagant's forces, flaming arrows shot at the camp are sent in an overhead arc, to travel the required distance. When Malagant's forces are shot, the arrows are traveling at a near-horizontal trajectory, instead of falling from above.
Right before Guinevere jumps from her carriage, you can see the guy who is actually driving the carriage behind the seat. You can see his face through the hole or slit behind the seat and you can see the reins disappear into a slit just below the seat.
After Lancelot saves Guinevere the first time, she uses a small crossbow to shoot a guy trying to kiss her. She shoots the crossbow straight up into the guy's stomach. When the guy falls to the ground, the crossbow bolt comes out of the man's stomach horizontally, not vertically.