Question: During the go-cart race, several shoppers are sent flying by the errant carts, one of them an old man who yells "Little rascals" at the kids. He's not listed in the credits but I could swear the old man is Robin Williams in makeup.
Answer: That part was originally supposed to be played by Spanky McFarland, the original little rascal, but died before production began. So an extra was used.
I must ask, do you have a source to back this up? I can't find one and it also seems to contradict what other original cast members said. Some original cast members/children of original cast members stated they were not made to feel welcome on set and couldn't even get hold of the film to take part. They expressed disappointment at not feeling welcome. It would be interesting if they were welcoming to the original Spanky, but not some of the others.
Answer: That was Ryal Haakenson who mostly did background extra roles in the 1990s. This film, he was uncredited for this scene.
Question: Why is this movie called "The Little Rascals" instead of "Our Gang"?
Answer: Because MGM owned the rights to the "Our Gang" trademark, when the early films were re-released and new series started, the name was switched to "The Little Rascals" (for example, the 1982 cartoon) and that's what most people know them by. After that, it gets tricky with which companies own which rights, and King World Productions has some of "The Little Rascals" distribution rights.
Answer: I tried looking this up on the IMDb and couldn't find anything about Robin Williams there. My only suggestion is to watch it again and see if there is a list of extras in the credits somewhere. Maybe that's all the part was, an extra.