The actress's mother Blythe Danner said that she persuaded thespian friends David Cryer, Ken Howard and Rene Auberjonois to put on a performance of the musical at the bash.
Danner told People: "They did the whole Wizard of Oz. That was kind of spectacular."
Talking about her daughter's own parenting skills, she added: "She's an extraordinary mother. Her first allegiance is for her children."
Paltrow recently revealed that she was forced to hunt down a piñata, a bouncy castle and princess fairy paint for her daughter Apple's fourth birthday.