On Tuesdays, Jelfonzo will wear a shirt that has a lip design with a message in the Inklings' language on it. It would take 5 years after the game's release for this message to be translated into English from the Round script variant of the Inklings' language, revealing that it reads "FUCK YOU". The game's art book "The Art of Splatoon 2" features early concept art for the shirt where it was originally titled the "Rounded You Suck Shirt", which translated to English through the Bubble script variant reveals that it does indeed say "YOU SUCK".

In the Octo Expansion, during the cutscene where Telephone assembles all the Thangs, a distorted set of screams can be heard. Reversing the audio for these screams reveals that it's actually a group of people counting down from 10 and shouting "Happy New Year!", with each word in the audio clip being individually reversed so it still forms a normal countdown.

The Hasta La Vista Station title, tagline and mission text are all references to the Terminator franchise: The title is a phrase from the original 1984 film, the tagline "I know now why you ink..." is a reference to the line "I know now why you cry" from the 1991 sequel, the use of the word "terminate" for the mission description is unique to this mission (normally it is "defeat").

In the Octo Expansion, Stations Maverick, Goose, and Iceman are named after the nicknames of the characters from the film Top Gun. The taglines for these stations "Revvin' up your Inkjet...," "Listen to its howlin' roar...," and "Jet into the danger zone..." are references to the song "Danger Zone" by Kenny Loggins, which was used in the film.

In the Octo Expansion, the many titles and taglines of stations contain references to music from the 80s-90s:
• Roll Out Station - "Rollout" by Ludacris.
• Fake Plastic Station - "Fake Plastic Trees" by Radiohead.
• Bounce with Me Station - "Can I Get A..." by Jay-Z.
• "Just go ahead now..." Spin Docto Station - "Two Princes" by Spin Doctors.
• "Just cruisin'..." Rad Ride Station - "Just Cruisin'" by Will Smith.
• "Blowin' up like it's all good." Notorious Station - "Juicy" by The Notorious B.I.G.
• "Bring da ruckus!" Phat Splatz Station - DJ Phat Beatz and "Bring da Ruckus" by the Wu-Tang Clan.
• " Step it up!" Breakdance Station - "Step It Up" by Stereo MC.
• "As 50 yellow balloons go by..." Pop Rock Station - "99 Red Balloons" by Nena.
• "Ya like to..." Move It Move It Station - "I Like to Move It" by the Outhere Brothers.
• "Stamp-collaborate and glisten!" Stamped-Up Station - "Ice Ice Baby" by Vanilla Ice.
• "Don't just stand there..." Bust 'n' Move Station - "Bust a Move" by Young MC
• "Round round round round..." Right Round Station - "You Spin Me Round (Like a Record)" by Dead or Alive.
• "Splat magic splat!" Labyrinth Station - "Magic Dance" by David Bowie.
• "Watch out now!" Ink & Watch Station - "Watch Out Now" by The Beatnuts.
• "Gettin' dizzy with it..." Don't Ralph Station - "Gettin' Jiggy wit It" by Will Smith.
• Swass 8-Ball Station - Sir Mix-a-Lot album, Swass.
• "Inkulators, mount up!" Squee-G Funk Station - "Regulate" by Warren G and his record label "G-Funk"
• "Take it easy..." Slow Ride Station - "Slow Ride" by Foghat.
• "Don't stop 'til you pop enough!" Pop Star Station - "Don't Stop 'Til You Get Enough" by Michael Jackson, who was known as "The King of Pop."
• "Who let the pods out?" Duh-Oh Station - "Who Let the Dogs Out?" by Baha Men.
• "Might as well..." Jump Station - "Jump" by Van Halen.
• "What's the dealio?" Cubular Station - "What the Dealio" by Missy Elliot.
• "Y'all bready for this?" Toastmaster Station - "Get Ready For This" by 2 Unlimited
• Ride with Me Station - "Ride wit Me" by Nelly.
• "Ink it real good!" Ink It Station - "Push It" by Salt-N-Pepa.
• "My my my my..." Can't Touch This Station - "U Can't Touch This" by MC Hammer.
• "Can't c me..." All Eyez Station - "Can't C Me" by Tupac Shakur from his album All Eyez on Me.
• "Ink-a-zig-ah..." Girl Power Station - "Wannabe" by the Spice Girls.
• "Do not miss your chance..." One-Shot Station - "Lose Yourself" by Eminem.
• "Watch your step!" Footloose Station - "Gettin' Jiggy wit It" by Will Smith.

In the Octo Expansion, the title for Stick 'n' Move Station is a reference to a line in the 1979 film Rocky II, where the character Tony Evers tells Apollo Creed to "Stick and move." The tagline is a reference to Muhammad Ali's famous line about his boxing style, that he would "...float like a butterfly, sting like a bee!"

In the Octo Expansion, the taglines for all the 8-Ball stations are possible answers for a Magic 8-Ball:
• "Signs point to yes..."
• "Better not tell you now..."
• "It is decidedly so..."
• "You may rely on it..."
• "Outlook not so good..."
• "Reply hazy, try again..."
• "As I see it, yes..."
• "My sources say no..."
• "Cannot predict now..."
• "Don't count on it..."

Pearl and Marina's designs in the Octo Expansion are references to American rappers Notorious B.I.G. and Tupac Shakur, respectively.

In 2020, after Nintendo sent a cease & desist to the major Super Smash Bros. tournament The Big House for using emulated Slippi netplay in the midst of the COVID-19 pandemic, participants in an official Splatoon 2 tournament collectively changed their tags to include the phrase "#FreeMelee". Shortly after, Nintendo would cancel the tournament, with their statement simply pertaining to "unexpected executional challenges".

In response to this, the Splatoon community hosted their own tournament in tribute to The Big House, titled "The Squid House" - this would end up becoming the biggest Splatoon series tournament to date, attracting 7,000 viewers and raising $28,000 USD, with $3,000 going to charity while the rest went to the participants.