For the longest day of Summer, Phineas and Ferb decide to travel around the world in a specially-made rocket ship following the sun to make an almost 24-hour long day. Meanwhile, Doofenschmirtz travels to Tokyo along with his daughter Vanessa and a kidnapped Major Monogram to sabotage the "Annual Good Guy Convention" being held there.
- Affectionate Gesture to the Head: Done by Candace to Ferb in the final song sequence. And considering it's pretty much the only time so far that she's shown physical affection to her little stepbrother, it's nothing short of adorable.
- Animesque: Parodied during the most terrifying Caramelldansen Vid ever created, performed by Stacy's relatives in Tokyo. Isabella was holding a leek during the dance as well.
- Arbitrary Skepticism: Buford suddenly begins to doubt that Phineas and Ferb could follow the sun around the world, thus experiencing a 40 hour day, despite spending the whole summer with them and seeing all the incredible things they've done. Buford even lampshades this.Buford: There's nothing I've ever seen that would make me believe that you could pull this off...Except for that time machine thing and oh, and that roller coaster, and other than that, nothing. Oh, and that time you played that song and the platypus came back. Man, nature just bends to your will, doesn't it?
- Artistic License: The day before Summer Solstice, Phineas says their summer vacation is more than halfway over; in reality, Summer Solstice is the first day of the summer season altogether.
- Art Shift: The musical number done by Stacys cousins shifts to an anime-esque video.
- The Bet: If Phineas, Ferb and the gang make it around the world before the sun sets back home, Buford has to give them their bikes back. If not, they'll have to spend the rest of the summer doing nothing.
- Body Wipe: Candace's red shirt briefly fills the screen during her verse in "Summer Belongs to You".
- Break the Cutie: Isabella suffers this when her attempts to have a romantic moment with Phineas in Paris are continually sabotaged by his focus on getting the plane repaired.
- Breaking the Fourth Wall:Linda: It sure would be helpful if they could just make the days a little longer.
[A "ding" noise signaling an idea is heard as the bottom half of the screen is covered with an "advertisement" reading "You're Watching Television!"]
Phineas: Hey! Do you mind? We've kinda got a visual gag going on here!
[Advertisement disappears, revealing the "ding" was actually from Ferb with a triangle.]
Phineas: Thank you!
- Characterization Marches On: While in the second season a lot of the characters have undergone a fair personality development, but it's this episode that really skyrocketed with deepening the characters' individualities. Phineas showing that he's not completely resourceful, getting frantic once he's realized his perplexity and showing anger and impatience for once, Candace gaining belief in herself and things seemingly impossible, Vanessa accepting her father's quirks and peculiarity, Jeremy earning the ability to tell Candace about her annoying obsessive behaviour (which further led them to become an Official Couple), Isabella crossing the edge of her endurance to Phineas' ignorance towards her and revealing to be the only one able to encourage him into not giving up. Even Buford gets some screen time showing that he is fluent in French and can quote Voltaire from heart. Only Baljeet remained unaltered by the episode.
- Chekhov's Gun: This episode has a series of Chekhov's Guns in near-succession: Doofenshmirtz's giant water balloon, Ferb's map, the road construction, and finally Buford's stolen bikes.
- Continuity Nod:
- In "Swiss Family Phineas", Candace questioned how come Phineas and Ferb didn't make something to get them off the island and even suggests how they should have done it, including using a giant slingshot to launch them off the island. In this episode, they use a slingshot to launch a giant paper plane so they can leave this island.
- Clay Aiken and Chaka Kahn are wearing the "Summer All The Time" collection, which is oversized versions of Phineas and Ferb's wardrobe.
- Crush Filter: During "City of Love", the background is noticeably pinkish with hearts floating in the air. As Isabella grows more saddened, the background becomes disaturated and the hearts eventually break and litter the ground.
- Extra-Long Episode: This episode runs for one hour, longer than any other episodes.
- Hammerspace Hair: Ferb gets an extra pencil for Isabella out of his hair.
- Heart Symbol: Hundreds of hearts, full and broken, appear throughout "City of Love".
- Heroic BSoD:
- Phineas undergoes one when the gang is stranded on an island and he tries to figure out what to do to get off in time only to lose hope.
- Isabella gets one at the same time as she out her feelings to Ferb that he didn't even notice her in Paris, and thinks of giving up. She snaps out when she realizes how much the situation relates more to Phineas than herself.
- Last-Second Word Swap: "Well, that's not the Phineas Flynn I fell in...to...this situation with."
- Mood Lighting: When "City of Love" begins, the colors are vibrant and the sky is clear, but when Isabella becomes saddened near the end, the colors become slightly disaturated, and the sky becomes cloudy and dark.
- Mood Whiplash: Occurs in "City of Love"; what seems like a romantic love ballad suddenly turns into a heartbreaking one as Phineas is too focused on fixing the plane that he unknowingly hurts Isabella's feelings.
- Nice Job Breaking It, Hero!: While in Paris, Isabella wants Phineas to spend time with her, not knowing that they have a bet to fulfill and they're in danger of losing it.
- Oblivious to Love: Taken to extreme here with Phineas, as he has absolutely no idea Isabella is trying to seize a romantic moment with him in Paris and only assumes she's showing him suggestions on how to fix the plane. Furthermore, Phineas is not oblivious of the crush Ferb has on Vanessa and the crush Candace has on Jeremy, and the fact both of those groups had some alone time in the city of love. The fact Phineas is aware of the potential romance between those other couples is enough to drive Isabella to pencil-snapping head-explosion-imagining aggravation.
- Orbital Shot: Isabella has a brief one during "City of Love".
- Pep-Talk Song: "I Believe We Can" by Clay Aiken and Chaka Khan.
- Poor Communication Kills: Phineas suffers these in Paris, during the "City of Love" number as Isabella is trying to have a romantic moment with him. Whenever she points out a specific location, he misinterprets the meaning and thinks of something to fix the plane depending on what is shown.
- Reveal Shot: Before "I Believe We Can" as Phineas is delivering his Rousing Speech, he climbs onto the plane wing and we see what appears to be his feet stepping into view in close-up, then the camera zooms out to reveal the feet are really those of Clay Aiken in Phineas' clothes.
- Roundabout Shot: Phineas and Isabella have one as they dance during the closing song. Provides the trope's page image.
- Rousing Speech: Isabella gives one to Phineas, having snapped out of her Heroic BSoD thanks to having a Eureka Moment, in an attempt to never give up and not lose the bet.
- Series Continuity Error: At the beginning of the episode, Phineas mentions "we traveled through time twice", and Isabella says the same thing later on when attempting to break Phineas out of his Heroic BSoD. However, neither should be aware of this since in "Phineas and Ferb's Quantum Boogaloo" when Future Candace fixed the past, Past Isabella time traveled to the time of the beginning of said episode to give the boys the tool they need, thus canceling the plot of the rest of the episode entirely.
- "Setting Off" Song: "Bouncin' Around The World" by Love Handel, which plays during the montage of the gang...well, you know what's described.
- Stealth Hi/Bye: The rope-jumping robot suddenly disappears from the backyard offscreen between the time Perry returns and the time Linda comes. A later scene shows it got caught on the tail of the plane Doofenshmirtz and Vanessa are taking to Tokyo.
- Tears of Remorse: Isabella sheds these as she is telling Ferb about her feelings for Phineas being ignored.
- Too Upset to Create: Phineas is so upset that he might fail that he starts snapping at everyone around him and his usual ability to think up insane solutions on the fly won't work. Isabella has to snap him out of it as he gets more and more desperate.
- Trailers Always Spoil: Almost every promo spoils the ending, especially the final concert at the end. Said scene was even spoiled in a promo during the final commercial break in the original airing.
- Whole Plot Reference: This episode is an updated and modified version of Around the World in 80 Days, with a wager to travel around the world, numerous unexpected setbacks, and finally coming down to the last tick of the clock.
- Your Head Asplode: Happens to Isabella in one scene. She was actually imagining it.