When a mysterious planet threatens to collide with the earth, Phineas and Ferb scramble to avert the disaster while Buford prepares to meet the planet's alien race. During this, Candace has to wait until midnight to bust her brothers thanks to the "Bust Accord", and Doofenshmirtz uses a Sphere-Attract-inator to try and steal the world's largest ball of twine.
----
!! Tropes:

* AnswerCut: Phineas attempts to assure a panicked Baljeet that the world's top scientists are already doing something about the Whalemingo planet coming toward Earth. We then cut to the North American Planetary Defense Headquarters in Marion, Iowa, where everyone is already panicking.
-->'''Scientist 1''': Duck and cover!\\
'''Scientist 2''': [[CallBack My]] [[WesternAnimation/PhineasAndFerbTheMovieAcrossThe2ndDimension water]][[RunningGag melon!!!]]
* ArbitrarySkepticism: Baljeet does not believe one word of Buford's story about his alien encounter. (This despite the fact that he has seen aliens himself a few times before.)
* BaitAndSwitch:
** At midnight, Candace wakes her parents up and finds them huddled together...listening to records.
** Before the planet spring stabilises, Isabella grabs what she thinks is Phineas's hand, when in fact it's Ferb's, and tries to reassure her that everything will be okay.
* CallBack: Linda mentions earlier that day Candace tried to show a [[Recap/PhineasAndFerbGiAnts giant ant farm.]]
* TheCameo: Doof's slippers are modeled after Peter the Panda.
* CompanionCube: Buford apparently has a lucky tambourine. He ends up giving it to Tristen as a memento.
* ContinuityNod:
** Some of the entries in the Bust Accord are references to previous episodes, like Candace promising not to bust her brothers while operating a vehicle or other heavy machinery ("[[Recap/PhineasAndFerbTheSecretOfSuccess The Secret of Success]]", "[[Recap/PhineasAndFerbBubbleBoys Bubble Boys]]"), while Mom is at the beauty salon ("[[Recap/PhineasAndFerbTheMagnificentFew The Magnificent Few]]"), during a date with Jeremy ("[[Recap/PhineasAndFerbARealBoy A Real Boy]]"), or while covered in honey and hair (""[[Recap/PhineasAndFerbBadHairDay Bad Hair Day]]").
** Phineas and the gang check on their milkshake bar through their telescope. ("[[Recap/PhineasAndFerbOutToLaunch Out to Launch]]")
* FreezeFrameBonus: The Bust Accord that Candace signed is only on screen for less than a second, but all twelve conditions that she agreed to are fully legible.
* FunnyBackgroundEvent: One of the bulletin boards in Doof's apartment has a taped on signed message saying "Under no circumstances move this bulletin board". Of course Doof ends up moving it anyway, making one wonder why he put that message on it in the first place.
* GratuitousForeignLanguage: The "Double Dutch" song has plenty of (mispronounced) Dutch phrases:
** "''Volgen nu!"'' (Follow now!)
** ''"Touwtje springen!"'' (Jumping rope!)
** ''"Wat leuk!"'' (What fun!)
* InsaneTrollLogic: Buford somehow reasons that when two planets collide, it's like when you have two sets of keys, and keep one in the car. It stupefies Baljeet so much that he temporarily forgets what he was going to say, then lets out a frustrated BigNo.
* HereWeGoAgain: Apparently, Baljeet has heard the story of Buford's alien encounter millions of times already.
* LoopholeAbuse: Candace can only try to bust her brothers once a day. Midnight marks the start of a new day, so she uses this to her advantage.
-->'''Mom''': Clearly, we need a ''thirteenth'' amendment to the Bust Accord.
* MixAndMatchCritters: The alien whalemingos (named by Buford) resemble flamingos with bulky whale-like bodies.
* MyFriendsAndZoidberg: When Buford realizes both planets are about to collide, he declares they have to save his whalemingo friend, Tristen.
-->'''Baljeet''': And, Buford...?\\
'''Buford''': (reluctantly) And the Earth.
* RunningGag: Perry and/or Doof accidentally setting off Doof's double dutch machine and complying with the jump rope moves as called out by the song.
-->'''Doofenshmirtz''': ''(yawns)'' Perry the Platypus, how did you get caught in my double dutch machine? That's not even a trap!
* ShoutOut: The shot of Candace's silhouette against the green light of the Whalemingo planet is lifted right out of ''Film/CloseEncountersOfTheThirdKind''.
* SubvertedCatchphrase: When Perry re-enters the backyard, Phineas doesn't say "there you are", he instead says, "Hey, sleepyhead. Do you want a snack, too?"
* ThatPoorCat: Heard when Doof throws a piece of wood offscreen.
* WhatAreRecords: At midnight, Candace once again catches her parents at an inconvenient moment, listening to records.
-->'''Lawrence''': It's what we used to use for music when we were kids.
* WhenTheClockStrikesTwelve: Candace signed an agreement not to try to bust her brothers more than once per day. Her mother considered adding a new clause when Candace took advantage of the fact midnight marks the beginning of a new day, but fails once more, and has to wait another whole day (yes, 24 whole hours) before she tries again.
----