After Candace loses a gift that Jeremy made for her, Phineas and Ferb enter her subconscious to retrieve the memory of what it looked like so they can build an exact replica. Meanwhile, after Perry accidentally catches Dr. Doofenshmirtz in his underwear, Doofenshmirtz has an idea: he decides to build a machine that will expose the underpants of everyone at the Tri-State Summit and Weenie Roast: The Underwear-Inator.
Tropes:
- Absurd Phobia: Irving has a fear of the color lavender, while Baljeet has a fear of contractions.
- All Psychology Is Freudian: There are several references to Freud, especially during the song and when Buford talks to Candace's Id.
- Appearance Angst: At the Falls of Anxiety, we hear some of Candace's anxieties such as worrying about her neck being too long or about wearing the same thing every day.
- Borrowed Catchphrase:
- Baljeet attempts to say "Where's Perry?", but due to his fear of contractions, forces himself to say it as "Where is Perry?" instead.
- When Gretchen gets eaten by the monster, she yells out, "Gretchen is out, PEACE!"
- Call-Back: Buford says "You all signed the leases, right?" in a similar manner to how Phineas says "You all signed the waivers, right?" in "Rollercoaster".
- Chekhov's Gag: Baljeet's fear of contractions comes into play later when Irving gets hit by the Underwear-Inator and has a mental breakdown when he realizes it's lavender colored. One of the kids needs to wake up in order to shut off the mind machine; the kids manage to wake up Baljeet by yelling out several contractions.
- Continuity Nod: The song "Deep Into Your Mind" contains a reference to "Squirrels in My Pants" from "Comet Kermillian", as well as several recurring elements/gags such as Candace's parsnip allergy, her bad relationship with Suzy, the talking zebra that calls her Kevin, and the Giant Floating Baby Head.
- Comedic Underwear Exposure: Doofenshmirtz attempts to invoke this with the Underwear-Inator. He gets the idea after Perry accidentally catches him in his underpants.
- "Could Have Avoided This!" Plot: Candace assumed that she lost Jeremy's gift. Turns out, it was just a drain un-clogger.
- Cutaway Gag: Baljeet says he is going into Candace's mind because he spent two weeks at psychology camp the prior summer.Student shrinks: So how did that make you feel?
- Journey to the Center of the Mind: The gang travels deep into the subconscious mind of Candace to retrieve her memory of Jeremy's gift.
- Shout-Out: On the bus, when it goes into a bad cell area, an old woman shouts, "My fillings are heating up!" This is most likely a reference to a story that Lucille Ball told Dick Cavett about her fillings somehow picking up radio transmissions. (There is still debate as to whether or not this actually happened.)
- Smash Cut/Mood Whiplash: As Baljeet is trying to cut the wires to the mind machine, Candace's Id eats two of the Fireside Girls, and eventually, the rest of the gang. The scene then abruptly cuts to the gang, unharmed, walking outside the backyard, saying "That was fun!" and "Let's do it again!".
- Solar-Powered Magnifying Glass: Perry pulls out a contact lens, holds it towards the sun, and uses it to burn a hole in the rope trap he has been captured in.
- Stalker with a Crush: Even though Candace and Jeremy are officially girlfriend and boyfriend, Candace still uses cameras, telescopes, and binoculars to watch him walk past her house.
- Visual Pun: During the song, Candace opens up a closet full of skeletons.
- Voice of the Legion: Candace's Id speaks this way, sounding like a combination of Dan Povenmire and Ashley Tisdale's vocals.
- Whole-Plot Reference: To Inception. The music throughout is also patterned after that of the film.
