Perhaps one of the most important lessons to learn early on in your photography is to pay attention to the background.
Often in a moment of great excitement we snap an image only to look at it later and see light pile protruding out of someone’s head. On occasion the result can be humorous but that is the exception and not the rule.
I would venture to say that after you have mastered colour and exposure of an image to match what you see, the next biggest contributor to a moment not appearing in the still image in the same way you experienced, it is the lack of attention background when taking the image.
Sometimes though, the decisive moment happens in the background. That was the situation in this image at least. While I was trying to capture the boy enjoying his pizza, I did not notice at the time Mom’s reaction in the background. It made the image for me at least.