Joe Pesci deliberately avoided Macaulay Culkin on-set because he wanted Culkin to think he was mean.
Everyone on-set was amazed with how mature and professional Macaulay Culkin was. Joe Pesci told Entertainment Weekly, "Mac is not like a nine-year-old. He's an old man already."
During production, Joe Pesci and Daniel Stern felt indifferent about the movie's potential, and neither of them believed that it would be a massive success. Their over-the-top performance in the movie was intentional.