Overall, I think you did a very good job with this entry GloriousShadow.
That straw roof looks beautiful, I need to try that in a MOC sometime... Lots of exciting action going on as well, and you included a nice amount of cruelty, using a flag for blood is a nice idea that I've never seen before.
The explosion effect on the white wall is perfect and adds so much to the entry.
Some improvement ideas:
1) I'm not a big fan of the dark red as blood, especially on the man with the dark red torso. Perhaps you could change it to red or trans-red.
2) The first picture in the one that will be judged, so I strongly suggest taking one that shows everything.
3) Your 3rd picture is quite hard to see, because of all the shadows, not having a white background is fine, but definitely try taking it when there aren't so many shadows outside.
4) You probably don't have the right pieces, but if you do, changing some of the weapons that don't fit in well with the time period such as the rifle and revolver would be great. Of course you could also remove them altogether, which I don't think would look too bad.
5) The SNOT water looks great, but it doesn't seem to match up exactly with the shore, as there's a little gap. It's hard to tell how to fix this from the picture, but I think it would be wise to put it right against the beach.
6) If you have a scared head for the man on the right side dangling off the wall, using it would look fantastic.
7) Some more hair or hats for the minifigs without them always adds a lot in my opinion.
8) The purple man on the ground could use a little more blood, since he's cut in half.
Nice job with your entry!
It has tons of great elements to it, and I think that if you fix some of the minor problems, it would be fantastic.
Good work and good luck in the contest!