Actually, that was a top-secret "weapon" - a decoy, used by the enemy in an attempt to lure you closer in toward shore for the local fisherman to surround your boat and be able to throw dead flounder at you. If you had higher-power zoom, you would notice that it is nothing more than painted plywood. A trick they learned from the Americans as they were preparing for Operation Overlord...
Actually, that phenomenon can happen in stock, or any of the mods, if the "author" of the files isn't careful, as you've seen in FotRSU...
If a group is routed over land anywhere in its journey, it'll be fine, so long as you aren't within the "spawn range" when they cross it. While in the digital netherworld, no issue, but as soon as they have to spawn, "crunch" - obstacle, and "collision detected". You should have seen Truk about a year ago in FotRSU...
