I have my Super Mario World Cart from 1991 and I recently picked up another Super Mario World cart for a friend and noticed that my cart had the Super Mario World side by side while my friends has the Super then under it Mario World also the Background is lighter on his!! Also on the top of the cart I have Super Mario World in center and in Bigger font while his is smaller font and shifted to one side, what made me approve that mines was a 1991 release was the fact of the serial # on the cart SNS-MW-USA (me) -- SNS-MW-USA-1 (his)
Have I discovered something here?













