Pinkie's line, "Something is rotten in... whatever the name of this village is", is a play on the line "Something is rotten in the state of Denmark" from Hamlet.
Starlight's rallying call "no pony left behind" in the song In Our Town mirrors the negative effects of the controversial No Child Left Behind Act that requires everyone meets a minimum goal but does not set higher standards for gifted individuals.
Throughout the episode, while dealing with Tank's hibernation preparation, Rainbow Dash goes through the five stages of grief, also known as the Kübler-Ross model.
Rarity is seen carrying a light blue and yellow bobble hat, a dark blue and red bobble hat is seen in a bag, while Fluttershy is seen putting a green ushanka on a beaver. These are references to the characters of Eric Cartman, Stan Marsh, and Kyle Broflovski, respectively, from Comedy Central's animated adult sitcom South Park.
The name "Tree Hugger" is a term commonly used, sometimes derogatorily, to refer to environmentalists and nature conservationists.
The Smooze is based on the Generation 1 villain of the same name.
The title is a play on the phrase "make new friends but keep the old."
Discord briefly appears in a cardboard box with a red exclamation point over it—a reference to Konami's Metal Gear video game franchise.
Discord says "Oh, you know what, I am famished, I'll take all the cakes." After finding out Pinkie Pie is taking her sister to the Grand Galloping Gala, he states, "You know what, cancel my order," and vanishes. A similar event happens in the Star Trek: The Next Generation episode "Deja Q" where Q, having been turned human and banished from the Q Continuum, has never eaten before and is "in a dreadful mood" and proceeds to order ten chocolate sundaes since he is "in a really bad mood, and since [he's] never eaten before, [he] should be really hungry", only to cancel his order after an unpleasant experience. [dubious – discuss]
The Smooze and Discord wear Harry Dunne and Lloyd Christmas's tuxedo and top hats from the 1994 comedy film Dumb and Dumber.
Rainbow Dash and Pinkie Pie pass by two griffons playing a game reminiscent of Dungeons and Dragons.
Gilda's grandfather Gruff seems to be based on Grunkle Stan from the Disney animated series Gravity Falls, sporting the same elder appearance, wearing a red fez and gold-digging mannerisms.[dubious – discuss]
The choice Gilda makes between saving Pinkie Pie and Rainbow Dash and recovering the Idol of Boreas is reminiscent of Indiana Jones' choice between escaping the Temple of the Sun and claiming the Holy Grail in the 1989 film Indiana Jones and the Last Crusade.
The Idol of Boreas is a reference to the Greek god of the north wind Boreas near whose cave Arimaspi-griffon conflict is said to have taken place.
Jeff Letrotski's cutie mark is a rug, specifically the scene where someone urinates on The Dude's rug. Walter's cutie mark is a briefcase, alluding to the film's ransom plot.
During the pan shot of the wedding guests during the Mayor's speech, Jeff Letrotski and Walter are visible in the third row on the right side. Donny is apparently absent, but Walter is holding a red coffee can with a blue lid. This alludes to the scene where Donny dies of a heart attack and Walter carries his ashes in a similar-looking coffee can.
The scene in which DJ-Pon-3 and Octavia Melody race through Ponyville on a mobile DJ station and pick up several bystanders is based on a similar sequence in the Kick Buttowski: Suburban Daredevil episode "Runaway Recital", which M.A. Larson also wrote.
During this scene, DJ Pon-3's mobile DJ station jumps over a toy shark for a brief second. This is a reference to the phrase "jumping the shark", which refers to the point where a piece of popular culture, usually a TV series, declines in quality and gives in to programming gimmicks so much that it becomes unwatchable. The phrase originated from the Happy Days episode "Hollywood: Part 3" wherein Fonzie literally jumps over a shark whilst waterskiing with his leather jacket on.
The episode's title is a reference to "party pooper", a person who doesn't want any fun, happiness, or enjoyment.
Prince Rutherford says, "Yaks smash!", which is a parody of the Incredible Hulk's catchphrase, "Hulk smash!"
Pinkie Pie briefly appears in photographs with a band resembling the Beatles. In one of the photographs, Pinkie and the band recreate the Fab Four's 1964 American debut on The Ed Sullivan Show. In another, Pinkie and the band are seen walking across a street, mimicking the album cover for the Beatles' Abbey Road. In yet another, they recreate the album cover of Sgt. Pepper's Lonely Hearts Club Band.
Pinkie Pie sitting backwards on Twilight while she is flying is reminiscent of the famous scene from the 1964 film Dr. Strangelove where Major T.J. Kong (played by Slim Pickens) rides a falling nuclear bomb.
Big McIntosh's transformation into an Alicorn is reminiscent of the transformation sequences of Usagi Tsukino transforming into Sailor Moon from the 1992 anime series Sailor Moon, complete with sound-alike music to the original Japanese version and the Viz Media redub.
Lyra and Sweetie Drops' fused dream form, being conjoined at the waist, is a reference to the characters Cat and Dog from the 1998 Nickelodeon cartoon series CatDog.[dubious – discuss]
Rarity introduces one of her dresses under the name "Tripping the Light", to which Fashion Plate responds with "Fantastic!". This is a parody of the phrase "Trip the light fantastic", which means to dance in a light manner.
The music heard during Pinkie's delivery montage sounds similar to the Clarinet Polka.
The face Pinkie Pie makes when she tries to resist the urge to tell the secret as Shining Armor and Cadence are about to tell Twilight parodies Roger trying to resist finishing the "Shave and a haircut" routine in the 1988 film Who Framed Roger Rabbit.[dubious – discuss]
The book being read for the animals' book club is Wuthering Hooves, a parody of Wuthering Heights by Emily Brontë. The hero of the book, Hoofcliff, is a parody of Heathcliff from the same book.
The giant cake containing the Hooffields in order to attack the McColts from their territory is similar to the story of the Trojan Horse.
According to director Jim Miller, the coloring of the Hooffields and the McColts was inspired by the colors of Curt and Punkin'head Martin from the 1950 Robert McKimson-directed Bugs Bunny short Hillbilly Hare.
Countess Coloratura makes her entrance in a giant bronze capsule carried by her backup dancers, just like when Lady Gaga was carried in an egg by her backup dancers at the 53rd Annual Grammy Awards.
Svengallop's name and characterization references the character Svengali from George du Maurier's 1895 novel Trilby, who seduces, dominates, and exploits the titular girl and makes her into a famous singer.
The unicorn who gives Countess Coloratura's voice autotune is a ponified version of Prince.
The music heard during the factory sequence at what was once Sweet Apple Acres is reminiscent of the Raymond Scott jazz composition "Powerhouse", made famous by its usage in many Warner Bros. Looney Tunes and Merrie Melodies cartoons.
The atmosphere in the timeline where Sombra rules over Equestria reflects that of America during World War II.