No, i mean all of it, the lighting is all over the place and some images do not even have lighting (e.g. the trapezoid platform or the round enemies). Check this:
Also there is pixel inconsistency outside of the asteroids with the "round explosion" using 2x2 pixels (bottom right, green text). Finally there seems to be some synchronization issue with some of the objects - the two objects with the yellow arrows seem to slide back and forth a single pixel as the screen scrolls. BTW what is the brown object? It seems to lack form/definition compared to the other objects.
These are static objects so it shouldn't be hard to fix - just decide on a single primary light direction (top left is very common) and adjust everything follow that.