I remember when Bigfoot3290 pointed that out in 2005 in a flash movie.
I checked my original SMB cartridge, and had to basically put my eye on the CRT TV I use to see if it's there, and it is!
They say it's a thumbs up, but wouldn't/shouldn't the digits be on the sides of the hands instead of the center?
"Do you realize what this means? We've been getting flipped off by that shroom headed freak for 20 years." -Bigfoot3290