Tropes:
- Alternate Timeline Ancestry: Bart goes back in time and selfishly ruins his parents' first meeting, ensuring Marge never falls for Homer. He initially fears that this will erase him from existence, but instead discovers that he, and his sisters Lisa and Maggie, are now the children of Marge's old boyfriend Artie Ziff (and have gained his hairstyle, to boot).
- Anachronism Stew: When the Mayans figured out when the world would end, they decided not to worry and that Obama would be blamed for it.
- Played for laughs, when the Neanderthal version of Homer is offhandedly mentioned to actually come from the Renaissance.
- Black Comedy Rape: Homer is forced into three-way sex with two demons to save his youngest daughter. Subverted when Homer removes his clothes and suggests an unnamed sexual technique he wants to try, which grosses out the very demons who want to rape him. (May double as Too Kinky to Torture.)
- Bowdlerise: Channel 4's broadcast of the episode makes the ending of "Unnormal Activity" a Downer Ending as it removes Homer agreeing to a three-way with the demons - the segment abruptly ends after Lisa's complaint of her not being the favorite child almost gets her taken by the demons. They take Maggie back, and it cuts to black.
- Brick Joke: In "Homer and Bart’s Excellent Adventure", a man in 2012 is holding a placard reading “America out of the Middle East”. In 1974, a younger version holds a placard saying “America into the Middle East”.
- Broken Pedestal: Poor Lisa falls victim for this trope when at first, she is credited for the creation of the Subatomic Supercollider but when it backfires, she is told off by Mayor Quimby.
- Comic-Book Time: "Bart and Homer's Excellent Adventure" explicitly takes place in 2012 but reestablishes 1974 as the year of Homer and Marge's first meeting as high school seniors, which, if you took it seriously, would put them in their 40s by 10-year-old Bart's birth in 2002.
- Foreshadowing:
- Bart's time travel to 1974 is foreshadowed by a comic book cover titled "Fantastic Foreshadowing".
- Co-executive producer Joel H. Cohen's Halloween name is "Black Hole H. Cohen (spoiler alert!)"
- For Want Of A Nail: The only major world changes as a result of Homer not marrying Marge is that Richard Dreyfuss played Indiana Jones and Nelson is the Ziff’s butler.
- Found Footage Films: The entirety of "Unnormal Activity" is seen through video cameras.
- Future Me Scares Me: 1974 Homer is quite disturbed by his future self's appearance.
- Horrifying the Horror: Homer agrees to have sex with 2 demons to save Maggie and even establishes a safeword with the two before they start. As soon as Homer covers the camera, the demons yell the safeword because they are too horrified to continue or even start.
- Kid from the Future: Bart walks up to 1974 Homer and introduces himself as "the unwanted son from the future who kills all your fun."
- Me's a Crowd: To win Marge back, Homer gathers all the Homers from various times in history.
- Papa Wolf: When told that he has to have a threesome with 2 demons in order to save Maggie from hell, Homer begrudgingly does it after saying "It's one of those things a dad has to do".
- Parental Favoritism: To save her sisters from the demon they'd summoned, a young Marge promised to one day hand over her favorite child—which turns out to be Maggie. Lisa is dismayed it wasn't her until she thinks it through. The possibility that it could be Bart is, naturally, never raised.
- Safe Word: Homer and the demons agree on "cinnamon". Ironically, it's the demons who shout it first.
- Shout-Out:
- The title "Bart and Homer's Excellent Adventure" is based on Bill & Ted's Excellent Adventure, the title of the comic book that foreshadows Bart's Time Travel is "Fantastic Foreshadowing" and Bart's travel to 1974 includes a wormhole that features titles of James Bond films made between then and the episode's present time.
- "Unnormal Activity" spoofs the Paranormal Activity films.
- Staircase Tumble: During "Unnormal Activity", upon being woken up in the middle of the night, Homer follows Marge down the stairs and ends up doing this.Homer: We have stairs?! (Groans as he falls down the steps)
- Take That!:
- Bart describes 1974 as “a world where no-one’s mad at George Lucas.
- When Homer arrives to confront Artie Ziff and "take [his] life back":
Artie: I thought this might happen...so I mastered Brazilian Jiu-Jitsu! [lies on his back] Crawl atop me and meet your doom!Explanation - Too Dumb to Live: Lisa, of all people, does this in "Unnormal Activity". After learning that Maggie was the favorite, a bitter Lisa says "I thought I was the favorite!" but she quickly change her mind after the devil gives Maggie back and attempts to take Lisa instead.
