Very nice attempt at adjusting the spatial dimensions for the pumpkin; it definitely goes quite hand in hand with the scan. One little problem is the trees; a different blending mode for the trees is recommended because I see the blurry and non-connected areas on the smaller branches and twigs. The grass could also cover some more distance so it looks like it's disappearing as it goes into the horizon, and that is done by making the grass become darker towards the background (near the top). The same thing could be applied to the sky (the sky becomes darker towards the bottom). The text in the middle of the wallpaper also doesn't really belong (yes, text is very tricky, so you need a totally good eye to know which styles are suitable for the wallpaper). The colors are fairly decent, and your extraction is very nice.
Not to worry, Halloween will be safe for me because I don't plan on going outside to get beaten up by a bunch of eggs and going back to the dorm smelling like tomorrow's breakfast. XD Instead, I'll probably be online that day.
