I've never had an iffy with the quality nor the lighting, but the motion blur just caught me so off-guard because it, like everything else, made it just even more real than before. My latest ride, however, made me notice that as you fly by the towers right before you reach Hagrid, the natural curvature of the domes creates a distortion, making the tower look bent if you look to the left. I always thought they could fix it, but it would take lots of math. It's just very quick, though, so you don't really notice it.
On an unrelated note, I feel that the ride could use more music in various locations to allow for the experience to shine much more, like, for example, the dragon scene could have suspenseful brass with soft drums to convey the uneasiness and lost feeling you have when you're taken inside the bridge with the wood being all charred and broken. Or, perhaps, the dementors scene could really use some screechy violins to just make it that much more creepy. All things, in addition to a couple others, that could really benefit the riders' experiences.