Continuity mistake: The office in the book store changes from being quite large in the first season to very cramped and small from the second season onward.
Continuity mistake: The bathroom in Ellen's apartment, depending on where the shot is taken, is either seen as incredibly small, or when shot within the bathroom, quite large and spacious.
Answer: This groundbreaking episode was in the fourth season, episodes 22 and 23.
Jason Feng