Everyone on-set was amazed with how mature and professionalMacaulay Culkinwas.Joe Pescitold Entertainment Weekly, "Mac is not like a nine-year-old. He's an old man already."
Joe PesciandDaniel Sternfelt indifferent about the movie's potential during shooting, so they intentionally gave over-the-top performances, neither one of them believing this movie would become a massive success.
AlthoughJohn Hugheswas fiercely defensive of his screenplay and insisted that everyone deliver his lines as written, he allowed his friendJohn Candyto improvise. This was actually a trademark of writer and producer Hughes, who also had the five students inThe Breakfast Club (1985)improvise when they told one another why they were in detention. In the film, almost all of Candy's dialogue is improvised.