The song played in the background of Homer and Marge's daydreams is the most popular love song ever, called Happy Together.
Ms. Killebrew, the instructor at Camp Land-A-Man, is identical in appearance and voice to Millicent, the horse stable owner from Lisa's Pony. However it's never made clear if they're meant to be the same character.
Marge claims she enjoys Parliament but not Funkadelic in reference to the funk collective popular during the 70's. Both individual bands were led by George Clinton. Funkadelic was the heavier among the two individual bands, mixing heavy rock into the funk influence.
Homer's imagined perfect world includes Screaming Yellow Zonkers, Quisp flying by in his spaceship, and the Kool-Aid Man—whom Homer kills by drinking him.
Before meeting the Sea Captain by the docks, Homer says, "I guess it's Roe v. Wade, and it's my right to choose." This namechecks the landmark American supreme court decision on abortion.
When the Captain rows Homer across the lake to meet Marge, he sings: "I met her on the mountain, there I took her life. I met her on the mountain, Stabbed her with my knife." These are lyrics from the folk song Tom Dooley, as made famous by The Kingston Trio.
This episode shares the same major storyline as "It Happened One Summer (Parts 1 and 2)" from Who's the Boss, where Tony and Angela realize that they had already met as children and had even shared a kiss while attending summer camp.
Homer hints that his pen pal may have been Osama Bin Laden.
In this episode, Milhouse states that his kiss with Homer in the treehouse was his first kiss. However, in the season 3 episode, "Bart's Friend Falls in Love" Milhouse shared his first kiss with Samantha Stankey. It's possible he'd forgotten about that kiss.
When Homer notices the beer bottle in Bart's treehouse, he cradles it and laments that it "never had a chance be become [his] urine", essentially regretting that he never got to drink it. Seconds earlier, however, Homer had in fact drank the beer when Milhouse poured it out of the treehouse (although he was asleep and was unaware of where the beer came from).