When Doofenshmirtz's latest invention falls into the Flynn-Fletcher's front yard, Phineas, Ferb and their friends try to find out what it does. When Lawrence won't believe Linda, Candace helps her convince Lawrence to believe her (in an attempt to show Linda what it feels like when Linda doesn't believe her).

!! Tropes:
* ArtisticLicenseHistory: The documentary Phineas and Ferb watch says that the Roswell incident was in the 1950s. However, the actual incident occurred in 1947 and has since been debunked. The "spacecraft" debris turned out to be a weather balloon.
* BrokenRecord: "It's a bustin' feedin' frenzy! Stay outta the water! It's a bustin' feedin' frenzy! Stay outta the water! It's a bustin' feedin' frenzy! Stay outta the water!"
* ChekhovsLecture: Lawrence is busy giving a lecture on the eccentric Earl of Whiskershire, who owned a "spring-staff" used to disarm traps. He informs his audience that the original staff is enshrined in a statue of the Earl in the town of Cheddarton, England. Just then, Doofenshmirtz and Perry happen to be flying over Cheddarton, and Perry takes the Earl's staff from the statue, and uses it to disarm the traps on Doof's hover-skiff.
* ComebackTomorrow: Early in the episode, Dr. Doofenshmirtz can't think of something that his hover-skiff has more traps than. After it nearly crashes into Mt. Kilimanjaro, Doof suddenly blurts out "A golf course! A golf course has lots of traps!"
* ConnectedAllAlong: It turns out Dr. Doofenshmirtz dated Linda once, back in the early eighties.
* ContinuityNod:
** In the flashback, young Linda considers becoming a [[Recap/PhineasAndFerbFlopStarz pop star]].
--->'''Doofenshmirtz''': Oddly enough, she ''did'' become a pop star later. I'm still struggling with the whole "Tri-State Area" thing, but, you know, the dream is alive.
** At the beginning of the song, Phineas and Ferb are shown doing the walking dance from "Technology vs. Nature".
* DepartmentOfRedundancyDepartment: Phineas points out that they don't have to touch the machine because they have a portable electronic scanner, gumption, and ''another'' portable electronic scanner.
* FreezeFrameBonus: When Linda tells her children not to push the red button, Candace and Phineas have their pointer fingers sticking out, but Ferb has his right foot lifted in the direction of the button, with his shoe off.
* GayParee: When flying willy-nilly in Doof's rocket skiff, Doof and Perry flying over Paris, and as a joke, Doof calls out to "Pierre!", since it is a common French name.
* MyFriendsAndZoidberg: While trying to reverse-engineer the device, Phineas addresses his peers with "friends, [[FriendlyEnemy bullies]], [[FanBoy Irving]]..." Also serves as a "[[Theatre/JuliusCaesar Friends, Romans, countrymen...]]" parody.
* NiceJobBreakingItHero: Turns out, it was ''Linda'' who gave Doof the idea to become a supervillain and take over the Tri-State Area.
* OverlyNarrowSuperlative: While Doofenshmirtz and Linda are on their date, "What Do It Do?" comes on the radio. Linda says "Turn it up, I love this song!", and Doofenshmirtz replies, "Eh, it's okay, it's probably in my top seven, maybe eight songs about reverse engineering".
* PoorCommunicationKills: Linda asks Lawrence if he knows about the "thing in the front yard". Lawrence, assuming she meant the birdhouse he installed earlier, confirms that he was the one who built it, which worries Linda and causes her to eventually drag Lawrence back home.
* RuleOfThree: Zanzibar's "What Do It Do?" is played three times, first when the boys are watching TV, again in the car during the flashback of young Doof with Linda, and one more time as SuspiciouslyAproposMusic during the kids' montage of wondering what the robot does.
* SuspiciouslyAproposMusic: The montage of the kids trying to figure out what the robot does is accompanied by Zanzibar's "What Do It Do?".
* TertiarySexualCharacteristics: When the machine that Doof made falls in love with the one that Phineas and Ferb made, the latter suddenly gets eyelashes on its eye that weren't there before.
* UnwittingInstigatorOfDoom: Linda herself was the reason for Doof becoming an evil scientist.
* WelcomeToMyWorld: Linda expresses frustration over Lawrence not believing her regarding the giant machine in the front yard, and Candace takes the opportunity to explain this is how she feels whenever Linda fails to notice the inventions Phineas and Ferb build. Unfortunately, [[ArbitrarySkepticism this isn't enough to convince Linda to go see the boys' invention in the backyard like Candace wants her to]].
* WordSaladLyrics: In the flashback, Doof and Linda are listening to "That's Wings, You Turkey" by King of Loud.