We finally found out why Theodore was nick named "Beaver". It was because when Wally was little, he couldn't say "Theodore".
This final episode of Leave it to Beaver goes down in television history as the first traditional TV "series finale" (by today's standards) by ending with this "clip show." No other series prior to this had a special ending episode produced (with the exception of "Howdy Doody" in 1960--but it didn't use flashbacks and was not a sitcom!), they all just simply ended with a general story line that could have come at any point in the series.
Beaver: Hey Wally, let me wind it next time.
The last line in the entire series.
June: Hey look at this Ward.
Ward: What is it dear?
June: It's an old family scrapbook!
Jerry Mathers and Barbara Billingsley were the only actors to appear in every episode.
Through flashbacks, Ken Osmond, Sue Randall, Rusty Stevens, Madge Blake and Pamela Baird make their final appearances in their recurring roles of Eddie Haskell, Miss Alice Landers, Larry Mondello, Mrs. Mondello and Mary Ellen Rogers, respectively.
All guest stars appeared only in the scenes from previous episodes.