In addition to the vast number of things that happen Once an Episode, Phineas and Ferb has a bunch of Running Gags that might make it qualify for a gag marathon.
- "Aren't you a little young to be (insert dangerous job here)?" "Yes, yes we are."
- "Ferb, I know what we're gonna do today."
- "Hey, where's Perry?" "Oh, there you are, Perry."
- Candace and whatever Cassandra Truth she's trying to inform her Mom of this time.
- Isabella becoming visibly upset whenever someone uses her Catchphrase. Anyone but Phineas, that is.
- Doofenshmirtz and his Hilariously Abusive Childhood in various flashbacks.
- The number of times they play with the Catchphrase moments might also qualify.
- Doof's ridiculous traps for Perry the Platypus.
- Nagging Wife: "What did you expect, that a [object] would fall out of the sky?" And then it does. Sometimes on top of her.
- (insert character name) is out, peace!
- People mistaking Doofenshmirtz for a pharmacist. To be fair, he is wearing a coat similar to what pharmacists wear...
- "What if a satellite falls out of the sky?"
- The Lice Duo, Olga and Chicago Joe, are in (or at least mentioned) in several episodes. Never really explained, though...
- A pigeon will crash into anything Phineas and Ferb have built provided it is tall enough. Subverted in one episode where Ferb installs a sliding panel to let it through.
- Doofenshmirtz's evil jingle.
- Agent P's entrances to his secret lair, and by extension, his briefings with Major Monogram.
- In big chaotic crowd scenes, someone will be trying to protect their watermelon of all things.
- Buford saying, "I am so in love with her right now."
- Doof's inability to recognize Perry the Platypus without his hat.Doofenshmirtz: A platypus?
{Perry dons the hat)
Doofenshmirtz: PERRY THE PLATYPUS?! - What is up with the floating baby head?
- "Secretly, I'm very lonely."
- "The Viking is right!"
- Almost every scene that involves something being built or things being moved around will include the giant creepy-looking baby head from "One Good Scare Oughta Do It!" appearing at some point.
- Buford being secretly cultured. His fluency in French and Latin are examples of this.
- The talking Zebra that calls Candace Kevin shows up a lot, usually when Candace is dreaming or hallucinating. It's even been Lampshaded. She realizes she's dreaming, and says so. Jeremy says that it would explain the talking zebra, but she says that she sees him all the time.Phineas: I'm just saying that as a Non Sequitur, a talking zebra seems a little—Isabella: Forced?Phineas: Yeah, forced.
- Whenever there is panic in the streets, there is almost always someone carrying a giant marrow and yelling, "MY WATERMELON!!!"
- Buford expressing frustration that Phineas's jokes and puns get more laughs than his
