Jennette McCurdy, who voices the badger Becky, being part of a somewhat over the top girl duo who get up to crazy antics.
Kendall Schmidt, Carlos PenaVega, James Maslow, and Logan Henderson play 4 beavers who help the penguins, who tell them that they "Gotta Rush, Big Time."
Casting Gag: When the celebrity voice actors were replaced in the transition from the film to the series, Sacha Baron Cohen (Julien's voice actor in the movies) was replaced by Danny Jacobs. Jacobs previously played an impersonation of Cohen's Borat character in Epic Movie.
Fake Brit: Private's VA, James Patrick Stuart, is from California and is only half-British. Lampshaded during "Hard Boiled Eggy" when Skipper notes Eggy picked up "an adorably fake British accent" from Private.
Mason's VA is American, and according to Private, Mason himself is secretly Canadian.
There are a number of individual DVD compilations with episodes from the series, but they don't comprise of the whole series. Unless you want to watch the series on Netflix (if your region has it), you probably won't get the whole thing. The entire series used to air on Nicktoons for years...until NBCUniversal bought out DreamWorks and ordered all DreamWorks-related content pulled from Nicktoons.
The entire series was available on iTunes for a while, but the DreamWorks buy-out led to the series getting yanked off the service, as well. Unless you bought the series then, you're SOL.
Missing Episode: Several episodes appeared on DVD and/or Nickelodeon's website well before they made it to air. The last two episodes to be considered "missing" were "Truth Ache" and "Command Crisis", which appeared on the show's first DVD compilation but didn't air until November 2010.
The Other Darrin: Among the eight voiced characters common to the films and the TV series (as mentioned, Phil doesn't talk), four have the same voice actors across the board: Tom McGrath (Skipper), John DiMaggio (Rico), Andy Richter (Mort) and Conrad Vernon (Mason).
DreamWorks staff members Chris Miller (Kowalski) and Chris Knights (Private) were respectively replaced by Jeff Bennett and James Patrick Stuart
In an interesting case, many fans commented that they considered Jeff Bennett to suit Kowalski's egotistical nerdiness better than Miller, and wished that he'd been brought back in for the Penguins movie.
Danny Jacobs replaced Sacha Baron Cohen as King Julien.
In an interesting case of both this and Role Reprisal, Alex's appearance in the "Return Of The Revenge Of Dr. Blowhole" movie has Wally Wingert reprise his role from the first Madagascar video game, replacing his movie actor Ben Stiller.