Harpo Does Something Funny: While there were scripts, Mitch Schauer provided a relaxed environment for the voice actors, which enabled Nick Bakay and Richard Horvitz to ad-lib and talk over one another. It eventually became the norm, which got Mitch into the habit of informing other voice actors of the duo's improvisational habits.
Keep Circulating the Tapes: When Nickelodeon was releasing their back catalogue of Nicktoons in the late 1990s, this one and KaBlam! were the only ones to not get any VHS releases. It wasn't until Shout! Factory came along that the show got a commercial release, now in complete series form.
Missing Episode: "Bye Bye Beavers". Audio tracks have been found, but there presumably isn't any animation to go with it. Its companion episode, "A Tale of Two Rangers", was apparently never even finished.
One-Hit Wonder: Norbert and Daggett never do produce another hit beyond "Beaver Fever" in the episode of that name, and eventually their spotlight is taken by Barry.
Unfinished Episode: Dialogue was recorded for the series finale titled "Bye Bye Beavers", but it was never finished or aired, as per a rule stating that Nickelodeon series finales should not have self-referential humor about the series' end. (Supposedly, Nick considered breaking the rules for it, but ultimately left it unfinished due to the fact that the episode ended with the Beavers going to Cartoon Heaven, which was thought to be too sad for kids.) It was supposed to be paired with an episode called "A Tale of Two Rangers", of which no trace exists.