While the boys build a giant tire swing, Buford removes a particular part which accidentally turns Candace into a fly. Meanwhile, Doofenshmirtz suffers from evil scientist's block.

!! Tropes:
* AcquiredErrorAtThePrinter: Monogram received a message that Doofenshmirtz is at the "shark", but Carl informs him it was a typo, that he's at the "park", not the "shark".
* AddedAlliterativeAppeal: Major Monogram instructs Agent P to "Stop Doof from doing the doing that Doof does... do."
* AmnesiacResonance: The kids briefly break out into [[WesternAnimation/PhineasAndFerbTheMovieAcrossThe2ndDimension "Summer (Where Do We Begin?)"]]
-->'''Phineas:''' Yeah, we all know the song... [''goes wide-eyed''] But I'm not exactly sure ''how''. [''[[{{Beat}} Everybody stares blankly at the screen for a few seconds]], before continuing on as if nothing happened'']
** During this scene, Perry has a very apt look of concern on his face, since he worries that his cover is about to be blown again.
* AnimalSpeciesAccent: While turned into a fly, at one point Candace says her brothers are "so ''buzz''-ted!"
* AnimalTalk: In fly form, Candace can talk to other flies, but not to humans; they only hear her words as "buzz buzz buzz".
* AreYouPonderingWhatImPondering: After Phineas gets inspired to improve on the tire swing, he says, "Ferb, I know what we're gonna do today?", to which Buford quips, "Uh, hatch mosquitos?", to which Phineas replies, "No."
* BaitAndSwitch:
** Once Phineas accuses Buford of tampering with the machine, Buford says, "Uh... [[BlatantLies Oh no! If I catch the mug what did this...]] Yeah, I'm on it."
** When the giant tire swing ends up in outer space, an astronaut seemingly comments on this.
--->'''Astronaut''': Whoa, that is weird! We're in a space shuttle and [[https://en.wikipedia.org/wiki/Space_Shuttle_retirement the shuttle program ended years ago.]]
* BuffySpeak: Buford tinkered with the machine by "taking the doohickey out of the thingamawhatsit".
* CallBack:
** The gang at first suggests rehashes of old ideas. Buford first suggests making a "super-''duper''-[[Recap/PhineasAndFerbRollercoaster rollercoaster]]", and Isabella suggests making a "Portal to Venus" since they already made a [[Recap/PhineasAndFerbUnfairScienceFair portal to Mars]].
** In response to Phineas' asking what summer was all about, the others start singing [[WesternAnimation/PhineasAndFerbTheMovieAcrossThe2ndDimension "Summer (Where Do We Begin?)"]], prompting Phineas to point out that they all know the song... but no one's sure how.
* CreatorCameo: The fly with a human head that Candace talks to briefly is played by and modeled after writer Martin Olson (also the father of Olivia Olson, the voice of Vanessa).
* DodgyToupee: As a fly, Candace discovers that Bobbi Fabulous (the bass player for Love Händel) has been wearing a wig this entire time.
* EvolvingCredits: As always, with a new season comes different still shots at the end of the theme song, with stills from ''WesternAnimation/PhineasAndFerbTheMovieAcrossThe2ndDimension'', "[[Recap/PhineasAndFerbDoofDynasty Doof Dynasty]]", "[[Recap/PhineasAndFerbMoonFarm Moon Farm]]", "[[Recap/PhineasAndFerbTheRemainsOfThePlatypus The Remains of the Platypus]]", "[[Recap/PhineasAndFerbEscapeFromPhineasTower Escape from Phineas Tower]]", "[[Recap/PhineasAndFerbTriStoneArea Tri-Stone Area]]", "[[Recap/PhineasAndFerbExcaliferb Excaliferb!]]" and "[[Recap/PhineasAndFerbBullyBromanceBreakup Bully Bromance Breakup]]".
* ForcedTransformation: Candace is turned into a fly, with her human head still on a fly body. Later, she meets a fly that was apparently hit with a ray that turned his head into a human's.
* InventionalWisdom: Phineas and Ferb invent a machine that makes sorbets that also shoots rays that turn humans into flies if some wires get crossed.
* LampshadeHanging: While complaining about his "evil scientist's block", Dr. Doofenshmirtz remarks that it feels like [[ComicBookTime this summer has been going on for four years]].
* PretentiousPronunciation: While inside Jeremy's room, Candace overhears him planning to take her to the rodeo, so she dresses up as a cowgirl. However, it is revealed that the place Jeremy plans to bring Candace to is a fancy restaurant with its name pronounced "Ro-DAY-o."
* ShoutOut: During the montage of Doof getting his groove back, at one point, Doof does a painting in the style of Creator/ReneMagritte's ''The Son of Man'', which depicts the surrealist artist with an apple in place of a face, but with Perry in place of Magritte.
* SpecialGuest: Robert Lopez (''Theatre/AvenueQ, Theatre/TheBookOfMormon, WesternAnimation/Frozen2013'') returns to co-write the title song.
* TrainingMontage: Somehow Doof has gathered from Perry's expression that he will "lead [him] through a series of bizarre and seemingly unrelated exercises that will help [him] get [his] groove back".
* UngratefulBitch: Somewhat zig-zagged. After being turned back to normal, Candace profusely thanks her brothers, but then returns to say "I mean, '[[CatchPhrase You are so busted!]]'", but then returns to thank them again.
* WholePlotReference: To ''Film/TheFly1958''. At one point, Candace says the iconic line, "Help meeeeeeeee..."
* WritersBlock: Doofenshmirtz has "evil scientist's block", preventing him from coming up with fresh, clever ideas for evil schemes.
-->'''Doofenshmirtz''': I was going to make a "good idea-inator", but then I thought that would be counterproductive, since that already had "good" in the title, so then I made a "bad idea-inator", which... just gave me this. See where that got me.
* YouKnowWhatTheySay: When the giant tire swing crushes Doof's perfect inator, Doof relates what his uncle Boris used to tell him, "When life's goin' well, a giant tire comes along and smashes your inator."
-->'''Doofenshmirtz''': We all thought he was crazy at the time, but now it seems rather prophetic.