another little thing to notice, the little white dingy in the top pic, not in the 2nd or the tird but in the last :- Could be very coinsadentle but I think the probility of that is extremaly low. Cosidering everything else in the first and last pic are the same. 
 
EDIT: ANOTHER thing, now this can't be coinsadence but the cars as well, exactly like the boat, picture 1 and 4 have the same cars on them, where as 2 and 3 don't  :D"  Dam i feel clever  :)  :D  (Y) 
 
EDIT AGAIN: Also note the cone at the bottom left corner on pictures 2 and 3 and next to it the upside down boat, its not there in picture 4 :D