Misperceived Monotreme

Sorry to be so harsh Agent P, but today is a very special day: Your one-hundredth battle with Dr. Doofenshmirtz!

Perry misses his 100th battle against Dr. Doofenshmirtz when Candace takes him to the Charity Pet Wash with her. Perry's absence goes unnoticed when the zookeeper's typical platypus at the Danville Zoo stops Dr. Doofenshmirtz's plan to zap his brother with his "Least Likely-inator." Meanwhile, the boys build a fun house Phineas and Ferb style.

Episode Summary
One day, while Phineas and Ferb were watching a news in the Danville zoo about their latest new animal, a platypus that likes eating sandwiches, the interviewers decide to to go see some other animals in the zoo. When they weren't looking, the platypus escapes into a delivery truck, as it smelled a sandwich that was left in there. Meanwhile, Linda calls Candace to do something instead of waiting for Jeremy until Candace gets a call from Jeremy. He tells her that they should go to a charity pet wash at the park. When Jeremy is talking about how a person's personality can be told by how they treat a pet, she decide to take Perry to the pet wash. Phineas and Ferb are thinking about fun that Ferb shows him that they should make a fun house. As Perry was going to his mission, Candace got him and took him to the pet wash. At headquarters, Major Monogram wonders where Agent P is and Carl was fixing his hover chair so it will go to Doofenshmirtz lair and goes back automatically, and he find Perry lair to be cute since it small like kindergarten.

At the backyard, Phineas and Ferb meet up with the delivery guy and after then delivery truck unloading all the stuff, the platypus from the zoo escapes out of the truck and walks toward the tree. Major Monogram still wonders where Agent P is, and ordered Carl while eating a sandwich to open all the entrances thinking Perry can't get inside to his lair. The platypus smelled the sandwich and enter the lair. Mistaking it for the real one, Major Monogram tells the platypus that today is the 100th battle against Doofenshmitz. They planned hidden cameras all over Doofenshmirtz Evil Incorporated to watch all the action, even seeing Doofenshmitz singing in the bathroom. Monogram sent the platypus to his mission in the hover chair.

At the pet wash, Jeremy and Candace tries to wash Perry but he tries to avoid getting a bath and escapes but failed. At Doofenshmirtz Evil Incorporated, Doofenshmirtz turns off a TV about the missing platypus in the zoo, the platypus arrives and Doofenshimrtz also mistaking it for the real one and quickly traps it throw the remove into a table. Doofenshmirtz shows and created the Least Likely-inator, which will make a person "do the least likely thing in their nature". He fires it randomly that Irving got hit by it tells Phineas and Ferb are losers and tries to flirt with Isabella.

Doofenshmirtz explains why he build the Least Likely-inator that would it makes his daughter obey him and his father love him, but the real reason was to humiliated his brother front of the legislator since it was least-likely he'll do and thus making Doofenshmirtz his successor in being the mayor. The remote that trap the platypus fell off the table,releases the platypus and started to lick a spilled coffee on the floor. Meanwhile at the Flynn-Fletcher house, Phineas and Ferb along with their friend starting to make the house into a fun house.

The platypus still licking the spilled coffee and thinks he's playing mind games with him. The platypus sees the sandwich display case that it runs to it and then crushes Doofenshmirtz with it trying to reach it. The sandwiches scatter on the Doofenshmirtz's devices that the platypus chases the sandwich and inadvertently avoid Doofenshmirtz's attack and turn some switches that Doofenshmirtz gets slammed into a brick wall and opening the roof. Candace and Jeremy finish giving Perry a bath and decides to go back at the Flynn-Fletcher house.

After arriving the house, everyone exploring the fun house but Perry tries to get out but only to get lost inside the fun house. Candace calls her mom outside about the fun house that she will come inside after picking up her grocery in the car. Doofenshmirtz tries to zap the platypus, but he throwing a sandwich in the hover chair that platypus run toward the sandwich and ride it back to Perry's lair and causes the Least Likely-inator to destroy itself after being turned around and manage to fires before it exploded. Candace got hit by the Least Likely-inator that causes her to clean the whole thing up unintentionally before Linda could see it.

Meanwhile, the platypus left the lair and Perry arrived. Major Monogram and Carl congratulated him despite not fighting at all and leaving him confused.

Songs

 * Quirky Worky Song
 * Livin' in a Funhouse
 * Shangri La

End Credits
Last verse of Livin' in a Funhouse

Whatcha doin'?
None.

Perry's entrance to his lair
Carl tests all the secret agent doors to see if any of them are jammed (Perry was late for his mission). The zoo platypus smells Carl's sandwich and instinctively walks into the tree elevator as it opens.

Evil Jingle
Doofenshmirtz Evil Incorporated!

Background Information

 * This is the second Season 3 episode to have more than one song.
 * This is the first time Jenny appears in an episode that Stacy does not appear in.
 * It is revealed that Doofenshmirtz's father is alive.
 * If one looks carefully when the platypus pushes the sandwich stand, he was on his hind legs like Perry, and his eyes were focused.
 * A part of the O.W.C.A.'s logo can be seen while Monogram and Carl are watching Doofenshmirtz. Also, when Perry lands on the chair in his lair at the end, Monogram mentioned the fight was a hit on the "'OWCA' internet".
 * The "Marsh" maneuver was most likely named after Jeff "Swampy" Marsh the creator of the show.
 * This is the first time that Phineas and Ferb's big idea is cleaned up by Candace.
 * Doofensmirtz was in the bathroom singing 'Shangri La', a famous hotel.

International Premieres

 * July 25, 2011 (Disney Channel Brazil)
 * July 25, 2011 (Disney Channel Latin America)
 * July 28, 2011 (Family Channel)

Errors

 * Along with "Ask a Foolish Question", most of the multiple line closed captions must be read from bottom to top instead of top to bottom.
 * It's unknown why Major Monogram, Carl, and Doofenshmirtz were unable to tell the difference between Perry and the Platypus that escaped from the Zoo. It may be colored that way so the audience can tell if it is a different Platypus.
 * When Candace picked Perry up whilst he was using his watch, in the next scene, the watch is gone.
 * In the opening scenes at the house, Perry doesn't have his top hairs, but while Candace is calling Jeremy, he has his top hairs again.
 * This is actually Perry's 118th battle with Doofenshmirtz (according to the list of episodes up to this point). we can also mention here that "Phineas and Ferb's Christmas Vacation!" in the future, also "Phineas and Ferb's Quantum Boogaloo", they hadn't fought in "Isabella and the Temple of Sap", and perhaps the events of "Unfair Science Fair Redux (Another Story)" count as the battle of "Unfair Science Fair" (also they didn't even fight in the redux, they went to the store), they hadn't fought in "Hail Doofania!", "No More Bunny Business", "I Was a Middle-Aged Robot", "Undercover Carl", "Traffic Cam Caper", "Perry Lays An Egg", "Thaddeus and Thor" and "The Monster of Phineas-n-Ferbenstein", also mention that "Phineas and Ferb Get Busted!" and "Wizard of Odd" were dreams, they hadn't fight in and which make a total of: 104 battles.
 * However, creators Dan Povenmire and Jeff "Swampy" Marsh confirmed the episodes don't take place right after the previous.
 * The mirror in the clip the O.W.C.A recorded was just triangles and a bit of Doofenshmirtz's hand and brush.
 * During the basement spin, the button on Ferb's shirt wasn't outlined.
 * When Major Monogram tells Carl he's in the way the ear piece on Carl's glasses disappear for a moment.
 * When Candace says "Oh, there you are, Perry", Perry's arm with the watch on moves suddenly.
 * Before Phineas and Ferb look at their blueprints for the funhouse, Ferb's shirt button is missing.

Continuity

 * Fourth time someone other than Perry goes to fight Doofenshmirtz. The first was Peter the Panda in "It's About Time!", the second time was Planty the Potted Plant from "No More Bunny Business" and the third time was the Dodo Bird From "Last Train to Bustville".
 * Third time Perry doesn't interact with Dr. Doofenshmirtz. First is in "No More Bunny Business" and the second is in "Undercover Carl".
 * Second time Perry is referred to as a monotreme. ("Swiss Family Phineas")
 * The giant floating baby head is shown again.
 * This is also the 3rd or at least time the guy with the name Steve is shown ("The Lizard Whisperer")
 * Ticks and tocks are heard again ("Don't Even Blink", "Make Play", "Unfair Science Fair Redux (Another Story)", " That Sinking Feeling").
 * Second time another platypus besides Perry is shown, though this time he is distinguishable from Perry, though only by his nose when he is smelling and his eyes, which are red. ("Oh, There You Are, Perry")
 * While Phineas is talking to Perry, the reporter can be heard telling the zookeeper that she had made the word "platypus" up, and then she said, "No, it's a real word." This is similar to a conversation Candace and Stacy had in an earlier episode ("Gaming the System").
 * Third time Ferb says the too young line. ("Vanessassary Roughness", "Canderemy")

Allusions

 * When Doofenshmirtz hits the brick wall, Monogram calls it the "Marsh Manuever". This is a reference to his voice actor, Jeff "Swampy" Marsh.
 * When Baljeet walks past the second last mirror in the Hall of Mirrors, he sees a monster-like version of himself. When he comes back, he is only stretched out, as the mirror normally would show him. This is the same in Disneyland's Haunted Mansion ride, only there are no fun house mirrors.
 * Stitch! The Movie and Lilo & Stitch: The Series featured a character with a single-minded obssession for sandwiches.

Cast

 * Vincent Martella as Phineas
 * Ashley Tisdale as Candace
 * Thomas Sangster as Ferb
 * Caroline Rhea as Mom
 * Mitchel Musso as Jeremy
 * Dan Povenmire as Dr. Doofenshmirtz
 * Jeff "Swampy" Marsh as Major Monogram
 * Dee Bradley Baker as Perry
 * Bobby Gaylor as Buford
 * Jack McBrayer as Irving
 * Lisa Ling as Takira Quawck
 * Alyson Stoner as Isabella