Phineas and Ferb made a guest appearance in an episode of Extreme Makeover: Home Edition in which they build a shrink ray to help Ty Pennington destroy a house.
Unlike most other shows, the cast does not record the scenes in the same room or even at the same time. Vincent Martella (Phineas) claims to have waited 2 years before meeting Thomas Brodie-Sangster (Ferb) in person. Part of the reason is that Thomas Brodie Sangster records his dialogue in England while the rest of the main cast is in America.
Interesting parallel: Vanessa Doofenshmirtz is the non (or slightly less) evil child of a Harmless Villain, who constantly snarks at his parenting attempts, similar to Scott Evil. Fittingly, her boyfriend Monty is played by Scott's actor, Seth Green.
Accidentally Correct Writing: That chattering sound Perry makes? Platypi really do make those noises in real life (though of course not with their teeth, which they don't have). Interviews have indicated that neither the show's creators nor Perry's voice actor were aware of this during production.
Jenny and Django are also confirmed to be siblings.
Banned Episode: From 2009 to 2015, "Ready for the Bettys" was rarely if ever shown in reruns due to legal issues with a real life band called The Bettys which the writers did not know about at the time. This issue also caused "The Flying Fishmonger" (which was paired with it for syndication) and "Phineas and Ferb Musical Cliptastic Countdown" (which features the song "Ready for the Bettys") to be pulled as well.
Seemingly every post-"Busted" Vanessa sighting has resulted in her character gaining a song, apparently due to Disney realizing voice actress Olivia Olson has an excellent voice. She does the singing for a lot of other female characters as well— "I'm Lindana and I Wanna Have Fun", for instance, and in "The Monster of Phineas-n-Ferbenstein", she voices the backup singers. AND according to her Wikipedia page, she's also written songs for the show.
She also gets songs in several episodes in which Vanessa doesn't physically appear, such as the Christmas Episode. (The songs tend to be "no one's actually singing, just accompanying a montage" songs.) In addition, there are episodes where she does appear (e.g.: the Star Wars crossover) just for the sake of singing songs rather than to advance the plot. It helps of course that her father (Martin Olson) is one of the show's writers and does some of the music for it as well.
Vincent Martella (Phineas) and Ashley Tisdale (Candace) get their share of time in the musical sun as well, though of course, they are the main (regularly speaking) characters.
Let us not forget Alyson Stoner. Interestingly, at first it didn't look like this trope was going to come into effect for Alyson, since initially every song Isabella was involved in either kept her in the background or replaced her voice as a gag (S'Winter). However, as of the Christmas special she's been getting some really nice numbers and even sings the main part on two recent ones, and that's not even counting her rendition of "Let it Snow" from the Christmas album.
Carl's voice actor, Tyler Mann, is a talented singer, but he didn't get to show off his chops until "Where's Perry?" This is lampshaded by Major Monogram who states "You may have some cleverly hidden singing chops."
Channel Hop: Sort of. From the second season onward, some new episodes premiere first on Disney XD as opposed to Disney Channel since the show skews more towards the former's demographic, and are then shown a week or so later on DC branded as "all new".
Well, sometimes a week or two. Sometimes six freakin' months.
As of "The Wizard of Odd", new episodes premiere on Disney Channel first again, but now they're labeled brand new when they premiere on Disney XD. As of the middle of the fourth season, they've begun premiering on Disney XDagain and are aired on Disney Channel as part of an "Disney XD on Disney Channel" block.
Another oblique example of Channel Hop, the series originally premiered on Toon Disney and remained when the network was transformed to XD in 2009.
"Princess" was written as a love song from Jeremy to Candace in "Make Play", the episode in which Candace meets an Identical Stranger Princess of Drusselstein. In songwriter Jon Colton Barry's own words, "It was decided Jeremy shouldn't have feelings for someone who isn't Candace even if she really IS Candace pretending NOT to be Candace. Do you understand? Me neither. Thus the song was chucked. Oh well. It was a cute idea".
"Summer Belongs To You!" — Buford would have expressed his nay-saying in "You're Wrong", which would have been followed by a "This Is Our Inspirational Song", a more tongue-in-cheek precursor to "I Believe We Can". Both can be found here. They also planned to include "The Ballad of Klimpaloon", which was eventually heard in "The Klimpaloon Ultimatum".
In his first appearance in "Dude We're Getting The Band Back Together", Johnny was voiced by John DiMaggio .
"Picture This" introduces Baljeet's uncle Maulik, named after Baljeet's voice actor Maulik Pancholy.
Dawson Casting: The main group of kids have ages 15 or under, according to the creators (with Candace being 15). None of their voice actors have ages falling into that range, with one of them [Maulik Pancholy] being in his late thirties. Incredibly, he's not even the oldest - the winner of that particular honour is Kelly Hu, who was 39 when she began voicing Stacy!
Jeremy and Vanessa were roughly the same age as their voice actors, Mitchel Musso and Olivia Olsen, respectively, during the casting.
Even though they voice teens on the show, both Musso (b. 1991) and Olsen (b. 1992) are actually younger than Thomas Sangster (b. 1990), the voice of Ferb, a preteen.
Descended Creator: Creators Don Povenmire and Jeff "Swampy" Marsh both voice the major characters of the show's recurring B plot; Heinz Doofenshirtz and Major Monogram, respectively.
DVD Commentary: "Attack of the 50 Foot Sister" and "The Chronicles of Meap: More Than Meaps the Eye" each have two: a standard one by Jeff "Swampy" Marsh, Dan Povenmire and Jon Colton Barry, and an in-character one by Dr. Doofenshmirtz and Major Monogram. The former episode's commentaries are on the DVD The Movie: Across the 2nd Dimension, while the latter episode's commentaries are on the DVD A Very Perry Christmas: Bonus Disc.
Executive Meddling: One of the best positive examples of this trope. The producers of the show asked to have a musical in every episode. So far, many of them have been really catchy and memorable.
Disney also suggested to create characters that would become Isabella and Baljeet, both of which are quite popular.
One executive suggested that Perry should get a girlfriend, only for the creators to say that he is "married to his job". This was even made fun of in the episode "Nerds of a Feather".
Fan Nickname: "Dorito and Golf Club" for the title characters, based on their respective head shapes.
Jossed: A NY Times panel had Dan and Jeff finally putting the bed the identity of Phineas's 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).
Long Runner: An interesting case due to Schedule Slip, though the series qualifies as one no matter what at least by typical Disney standards. If going strictly by season count, then Phineas and Ferb is still the longest-running series in Disney history with four seasons - but stuck in a multi-way tie in such with multiple other animated and live-actions series. When going by the actual length of time elapsed between the premiere of the first and last episodes, it's far and away the longest-running Disney series running through eight years from 2007 to 2015 and multiple Channel Hops (from Toon Disney to switching variously with Disney XD and Disney Channel).
Missing Episode: "Ready for the Bettys" was pulled from the broadcast rotation in the United States after a band from New York with the same name thought they were copying them, according to one of the writers of that episode. This caused the episode it was paired with, "The Flying Fishmonger", to be removed as well. The episodes are still available on Netflix, iTunes, and Amazon Instant.
The full episode was aired again on Disney Channel on May 22, 2015 at 5:00am, and aired on Disney XD (for the first time) on June 10, during the marathon of every episode they aired in anticipation for the Series Finale.
For whatever reason, the Musical Cliptastic Countdown Hosted by Kelly Osbourne is not available on Netflix.
Played with in "Summer Belongs to You"; when the first song begins, we hear a voice that is obviously not Phineas singing as we pan up a body dressed in Phineas's clothes...and then we find out that it's Clay Aiken, dressed in Phineas's clothes. And then Chaka Khan dressed in Ferb's clothes enters.
Played straight with Ferb, as Danny Jacobs, Dan Povenmire and Aaron Jacob have done his singing voice.
Played with and lampshaded in "Ladies and Gentlemen: Meet Max Modem!", when Linda mentions that she only lip-synced "I'm Lindana and I Wanna Have Fun". The person who actually sings that song isn't the same person who voices Linda. It's Olivia Olson, who voices Vanessa.
John DiMaggio voices Johnny in "Dude, We're Getting The Band Back Together". Starting from "Brain Drain" onward, he's voiced by Logan Miller.
In the Russian dub, both Phineas and Ferb had their voice actors replaced twice. Once for the second season, and once again for the third season and onwards. The differences between season 1 Phineas, then seasons 2 and 3 is very obvious. (Justified in a way: season one was dubbed in Moscow by SDI Sun Studio Russia, and the rest is done by Nevafilm, albeit in Moscow, too)
Fireside Girl Holly was voiced by Cymphonique Miller from season 1 to the middle of season 2. After that, Diamond White would take over.
Fireside Girl Ginger (Stacy's sister) was voiced by Tiffany Espensen from season 1 to season 2. Michaela Zee would take over afterwards.
The Amazon digital release breaks the four seasons into ten. The short seasons are mostly from the same full season, but in a completely random order (for instance the pilot is the eleventh episode). With the show's love of call backs and internal references this is very noticeable. The syndication order is slightly different than the production order, but nowhere near as blatant.
Save Summer was aired before The Klimpaloon Ultimatum, as it mentions the latter.
Split Personality was aired after Summer Belongs to You, as Candace mentions shes trying to make Jeremy her boyfriend in the former and they officially become a couple in the latter.
Pet Fad Starter: Notably averted. Dan Povenmire and Jeff "Swampy" Marsh were apparently Genre Savvy enough to be aware of this trope when they developed the series, which is why they deliberately gave their protagonists a pet that was uncommon, an animal that kids could not "pick out at a pet store and beg [their parents] for". Perry is a Platypus.
Phineas and Ferb was first pitched around 1990 with a pilot made for Nickelodeon in 1992, but lack of faith in the project and additional commitmentsfrom theshow's creators (hoping to get their big break that way), delayed the show for more than 15 years, finally premiering in 2007 on Disney Channel instead of Nickelodeon.
There was a movie announced in 2011, originally planned to be released in 2013 - later 2014, but was inexplicably removed from Disney's release schedule. But on April 11, 2019, it was announced the movie would be produced and distributed on Disney+.
Schedule Slip: The show officially has four seasons - which have been stretched across eight years from 2007 to 2015. Going strictly by season count, it's in a multi-way tie with a number of other animated and live-action shows for longest running Disney series, but going by calendar year run it takes the prize by an almost insurmountable margin.
Screwed by the Network: Despite the exact opposite. Phineas and Ferb are subject to frequent marathons and specials across both of Disney's major channels, and they play a big part in a lot of the channel bumpers and advertising, but during the middle of Season 2 new episodes were subject to some severe Schedule Slip, to the point where they would air in other countries months before the US premieres, which are about a month apart from each other themselves. The premieres have since been getting more regular since the start of Season 3.
Shrug of God: The creators, when asked Phineas and Ferb's age; though the original pitch was to make them nine-year olds. this was retracted so that now they're merely "less than fifteen".
In "Quantum Boogaloo", however, they had to pick an age, so ten was given, as twenty years in the future. Future Linda says that the boys are thirty years old. However, she may have been rounding; Word of God was that fans shouldn't necessarily take her literally.
"Act Your Age" takes place 10 years after the primary setting of the show, and Phineas and Isabella are getting ready to go off to college. This greatly suggests that they are only around 8-10 years old.
Jeremy was originally going to be an unseen character, with Candace and others only referring to him in conversation. Likewise, Stacy was going to be just someone Candace spoke to on the phone.
Planty the Potted Plant was going to get more screentime, but most of his scenes ended up being cut for time.
Carl was a completely accidental character: one of the writers just started having Major Monogram make aside comments to the guy operating the camera. The other writers loved it and began including Carl in the show proper.
There was suppose to be a theatrical film of the series, but it fell through and the series was giving the usual Made-for-TV one. It's unknown if Across the 2nd Dimension was to be that movie.
The bugs from "Doof 101" and The O.W.C.A. Files can be seen among the early character designs, but it wasn't until "Doof 101" that they found a use for them.
Dr. Doofenshmirtz was originally going to be called Meddleshmirtz, and Candace was going to be blond.
Dan and Jeff wanted considered making Perry a capybara, before deciding on a platypus.
The original plot to "Tip of the Day" was very different. It would've been an elaborate 22 minute-long episode about a secret society that keeps the word "aglet" from becoming common knowledge to prevent the end of civilisation itself. Dan and Swampy both flatly rejected this idea, and it was redone as a much shorter and simpler story.
According to this article made back in 2011 at the height of the show's popularity, there were plans for a spin-off series involving The Fireside Girls; but it never got made.
Swampy Marsh's twitter confirms the spin-off episode "The OWCA Files" was a pilot for another spin-off series. They never heard back from Disney if the show was going to be picked up, so they moved on.
Buford's "I Want" Song in "Wizard of Odd" had a full version planned out, but it was shortened to a gag in the final version to save time.
The 2-parter "Wheres Perry?" was originally called World Without A Platypus, and both parts originally served as the Season 3 finale and the Season 4 premiere.
In an earlier version of "Phineas and Ferb: Mission Marvel", Iron Man would have gained the ability to wield Thor's hammer after the powers get swapped. However, according to Swampy Marsh, this was shut down by Marvel. According to Marsh, conversation Thor and Iron Man have in the final version is based on their writers' conversation with the Marvel representatives about what can and cannot be done with the hammer.
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.