In ‘The one with the Embryos,’ Rachel and Monica bet their apartment in a personal trivia game against Joey and Chandler. When Ross asks the girls “What is Chandler Bing’s job," what does Rachel give as an answer?
Did you notice that Monica’s apartment changed from the number 5 to the number 20? This is because the writers realized that her apartment was on an upper level floor, so would be higher than 5. Joey and Chandler’s apartment then also changed from 4 to 19.