There is an early screenshot from an arcade flyer that shows players fighting two Allens. In the game, there is only one.
In the boss area of the first stage of Metal Slug 2/X, There are three banners with Arabic writing in the background. The first banner reads "Supermarket", but the second and third banners read "I have diarrhea." and "I need medicine." There are several other Arabic signs in the stage.