To put the bricks in perspective, just stagger what you've drawn so that the horizontal lines have about the same (or slightly lesser) slope as the line where the wall meets the pavement. You probably only need to stagger the bottom set, the top set seems to be close to the horizon and thus should have horizontal lines.
In the reflection, the Gengar seems to be standing on the very edge of the pavement rather than a little bit away from the edge. To communicate this, just hide the lower 1-2 pixels of the feet behind the pavement. We should probably also see more of the underside of the body.
Here's an edit changing the reflections and bricks. On the right, I also hue-shifted the colours more to make them look more interesting. The lamp emits a warm, yellow-orange light, the complement of purple. If you let that light colour the parts it lights instead of just making them a lighter purple, I think that'll help the colour scheme a lot, as well as make a more eye-catching composition. I made the highlights slightly more orange in my edit, but you could take this further and make it look better.
It took me a few looks to figure out the story in the scene. I think making the lollipop larger and giving it bigger chunk missing would help it read better.
Also, don't forget that the lollipop is affected by the same lights as the rest of the scene! It should not be so perfectly white and red.
