Happy Birthday and Too Many More - S3-E15
Other mistake: Laura is doing some work on when to have Richie's birthday, and Rob tells Laura "I thought we decided that about 8 years ago." Yet Mrs Billings has asked Rob to do 2 plays (1 each year for the PTA meetings) In the Happy Birthday... (Feb 1964) episode that would have made Richie about 10 due to the fact that Richie was 8 when "What's in a middle name" (Nov 1962) aired. (00:01:00)