I assume that you are asking about the effects in this story -- the things that come from the causes. If so, I think that the real effects are the ways in which the speaker and the other characters react to the hanging.
First, we see the effect of the condemned man stepping around the puddle. When he does that, the speaker realizes the enormity of what he is about to participate in. So that's the first major effect since it sets up the major tension of the story.
Second, we see so many of the man laughing and otherwise acting as if they did not care about the hanging. This is an effect of the hanging. The effect is that the people are somehow trying to deal with the stress of what they've just done.