The sergeant in "Phineas and Ferb Get Busted!" is Clancy Brown, aka Lex Luthor and Mr.Krabs. Clancy also voices a few other characters, such as Santa in the Christmas special and The Regurgitator in "Oh There You Are Perry"
In the same episode, Geraldo Rivera voiced an investigative reporter.
Sharp eared fans will recognize Ferb from Doctor Who. He is also the little boy from Love Actually, who has a crush on Vanessa who is voiced by the little girl he fell in love with in that very movie.
The early promos for the series jumped on the fact that AshleyTisdale and Mitchell Musso were providing voices.
Particularly amusing when BrendaSong competes with Candace for a job at Mr. Slushy Burger.
In in the same episode Brian Stepanek voiced The Slushy Burger Mangaer. Brian Stepanek also played Arwin in the same show.
Heck, the fact that Sharpay is best friends with Lady Deathstrike is awesome
Not to mention Jaret Reddick (the lead singer of Bowling For Soup, the band that performed the Phineas and Ferb theme song) as Danny in "Dude, We're Getting the Band Back Together."
Speaking of Love Händel, the drummer is Steve Zahn.
You may have recognized Linda Flynn's (Mom) voice from her stand-up, as Aunt Hilda and that she hosted The Biggest Loser for quite a few years... if you are of the older audience, of course.
How about Rico and Harper as Candace's future kids?
John DiMaggio voices an eccentric circus master in a commercial.
Don LaFontaine, announcing the opening of "The Chronicles of Meap"! The episode was one of his last roles in any film or series, and is dedicated to him.
In "Unfair Science Fair Redux," Tom Kenny voices an astronomer who has been watching a barren Martian landscape for lifeforms, on a huge screen, for 20 years straight. He finally flips out, unaware of Candace running across the screen.
He also voices the squirrel in "Interview with a Platypus."
For those familiar with Higglytown Heroes, Dee Bradley Baker was the voice of Pizza Guy.
And if you're not familiar with the latter show, you may know him as "every creature voice not done by Frank Welker"
My, that executive that Doof forces into watching a pitch of his at a convention sounds awfully like a certainfamilyguy! ... that's understandable, as the creators used to work on that show!
The background poster even says "Meet Jeff McGarland". So subtle...
It's shame Baljeet's uncle didn't tell everyone about that one time he taught the Avatar about chakras...
And she was thought to be cast as Kotori in the English dub of Yu-Gi-Oh! Zexal, but that's no longer the case.
In "Nerds of a Feather." both Kevin Smith and Seth MacFarlane do voicework in it, as stars in a Sci-Fi/Fantasy Convention. In fact Kevin's character looks like an older version of himself, and Seth MacFarlane plays a character named "Jeff McGarland".
In "The Beak", unfortunately named supervillain Khaka Peu Peu & his unseen chair throwing wife were played by Ben Stiller and his real-life wife Christine Taylor. An article in Animation Magazine said they agreed to do the show because their kids were fans.
Tara Strong shows up many times, voicing minor characters such as the bird in "Interview With a Platypus," and the woman in the audience in "Tip of the Day."
Jane Lynch as Mrs. Johnson and Tina Fey as Annabelle in "Run, Candace, Run."
Jossed: A recent NY Times panel had Dan and Jeff finally putting the bed the identity of Phineas' real father...kind of. They admitted that it was not Doof (thus throwing a loop in many a viewer's theory on the real parents).
"A Hard Day's Knight" comes across as almost a remake of "Are You My Mummy?" with one stock adventure lit antagonist switched out for another.
Word of Saint Paul: Long before Candace and Jeremy were an established couple, Jeremy's voice actor commented that Jeremy liked Candace back. Of course, it really wasn't all that hard to figure out, but still.
Both Marsh and Povenmire wrote for CatDog and Rocko's Modern Life. Both shows feature multiple minor characters with the name "Ferb."
At least three different cast members from the Rocky Horror Picture Show have starred or guest-starred in the series at least once. Richard O'Brien (Riff Raff) plays the father, Lawrence. Barry Bostwick (Brad MajorsASSHOLE!) plays Phineas's grandfather. And, Tim Curry (Dr. Frank N. Furter) guest-starred as a Mad Scientist in one episode. However, none of the characters nor their voice actors have interacted with each other as of yet.
As of "The Last Train to Bustville", Lawrence and Clyde, the grandfather, have had one, very awkward, conversation on camera.
Also at least 3 Lexx guest stars: Barry Bostwick (Thodin), Tim Curry (Poet Man), and Malcolm McDowell (Yottskry the Divine Cleric).
Ferb's Cousin Eliza fulfills the Grey DeLisle quota for a typical animated show.
