Now you've broke the map! I have seen this behaviours one before on my map, it was day one of the men map release. I thought I did something funky and (as I am not always playing with a clear head) could not reproduce the buggy sail. There is no way we can exploit this for double the sailing miles and EP reward I take it...
There actually is a Streak Buff titled "Chest Fest", the description being "Treasure Chest awarded for victory". You can see the icon for it zip past along with the other icons though streakbuffs_chest@ipad2x.png It seems it's not active server side though.
