Before the release of Tahm Kench. Laughing in the river of Summoner's Rift would result in Tahm Kench laughing back. This only worked once per match and only before Tahm Kench was released.

If all Champions on a team wear the Pool Party skins (including Rumble in the Jungle and Surfer Singed), a rubber duck will spawn in the bottom side river of Summoner's Rift.

By feeding a Poro with Braum, the Poro will grow a black mustache. When using the Dragonslayer Braum skin, it will grow an orange mustache instead.

In the ascension game mode if all 10 players dance, Xerath will dance as well. If one player stops dancing so will Xerath.

In Summoner's Rift, if Ahri wears the Popstar Ahri skin and dances in front of the Blue Sentinel, it will dance with her.

In ARAM, if all players feed a single Poro with 10 Poro-Snax, the Poro will explode into multiple smaller Poros.

After waiting for a few seconds on the Victory Screen in the Howling Abyss, Lissandra will give a monologue about the events that transpired on the bridge.

According to Riot, Yasuo uses Pantene to keep his hair beautiful.

When Braum feeds a Poro on the Howling Abyss map, the Poro will gain a moustache like his. The color of the moustache will change depending on Braum's skin.

When playing as Skarner and remaining idle for a period of time while in a bush, there is a chance for him to say "Skar-skar-skarner!" This is a reference to the Pokemon game series, in which each Pokemon says its own name in a similar fashion, and can be found within tall grass.

Ezreal's dance is based on the dance routine that appears during the ending sequence of the anime The Melancholy of Haruhi Suzumiya.

The developers made several April Fools jokes about a character known as "Urf The Manatee". Despite him never being a playable character, he has made an appearance in skins for the characters Warwick, Corki and Fizz. He was supposedly killed by Warwick, and on the Harrowing map, his ghost can come out and attack Warwick.

The name of the character Brand comes from the Swedish word for "Fire".

Nunu's "grungy" skin bears a strong resemblance to two Sesame Street characters: Oscar the Grouch and Cookie Monster.

There is a set of skins that are references to different web browsers:
• FoxFire Ahri
• Safari Caitlyn
• Explorer Ezreal
• Chrome Rammus

Draven can catch the axe of another Draven. Upon doing so, he will have special dialogue such as "Nice axe, I'll take it" and "Yoink!"

Heimerdinger's name is a portmanteau of the names of two famed scientists, J. Robbert Openheimer and Erwin Schrödinger.

Anivia's name will change to Eggnivia while she is in her egg form.

The champion "Blitzcrank" will sometimes say "Exterminate" when attacking, a possible reference to the popular TV show, Doctor Who.

King Rammus' design bears a strong resemblance to Bowser from the Mario franchise.

When two or more players dance in front of Vilemaw, he will do the "Carlton dance" from The Fresh Prince of Bel-Air.

Renegade Talon has red eyes and a rogue's bandanna covering his face. It's possible that Talon is the man who murdered Miss Fortune's mother, as according to her lore, "she saw her mother lying in a pool of blood. A sudden blow to her head made her collapse next to her slain mother. The last thing she could remember were her attacker's red eyes, as his face was blocked by a rogue's bandanna".

Mordekaiser's Ultimate Attack, "Children Of The Grave", may be a reference to the song of the same name by the British heavy metal band, Black Sabbath.

Mordekaiser's name means "Murder Emperor" when translated from German.

Shen has a strong resemblance to Joe Musashi, the ninja from the Sega game series Shinobi. The two ninjas also share the same walk animation and dash.

Thresh has a hidden passive where Nunu will drop 2 souls if slain near Thresh, one for Nunu (the boy) and one for Willump (the yeti). Strangely, Sejuani only drops 1 soul which is supposed to be 2, one for Sejuani, and one for her boar Bristle.

Nasus bears a great resemblance to the Egyptian god Anubis and the scepter he holds is similar to a Was, a scepter held by Egyptian gods.

Nasus' joke is a quote from the famous song "Who Let the Dogs Out?" by Baha Men.

Katarina's Shunpo ability is possibly a reference to a fictional technique in the popular manga series Bleach.

If Evelynn is seen by an enemy champion while in stealth, Evelynn will have an exclamation symbol as made famous by the Metal Gear Solid series.
The developer of the Stealth rework also claimed to get the idea of the rework from the Metal Gear Solid series.

Some of Ezreal's quotes are references to Indiana Jones quotes.

Ziggs /joke command is a reference to "The Mask", in-which Jim Carrey eats a bomb which explodes in his stomach and belches fire.

• Ahri's dance is based on the choreography for the song Run Devil Run by Girls' Generation, an extremely popular Korean girl group.
• Quinn's dance is from Aaliyah's music video "Are You That Somebody?"
• Malzahar's dance is based on the choreography for the song 'Can't touch this' performed by the famous MC Hammer.
• Vayne's dance is inspired by the Gun Kata. Gun Kata is a portmanteau of gun and kung fu, and is the style of sophisticated close-quarters gunplay. It often resembles a martial arts battle played out with firearms instead of traditional weapons.
• Rengar's dance is a reference to the New Zealand tribal dance, Maori haka, particularly the Ka Mate.
• Ziggs' dance is a reference to the "Indian Midget Superstar".
• Viktor's dance is a reference to the Melbourne Shuffle, a dance originating from Australia.
• Volibear's dance is a reference to Sam B's dance from America's Got Talent.
• Urgot's dance is a reference to Kirby's victory dance.
• Evelynn's dance is from the movie Flashdance, performed to the song Manhunt.
• Fiora's dance is a reference to Fred Astaire's dance in the movie Blue Skies, with the song "Puttin' on the Ritz".
• Janna's dance is a reference to Dance Studio's choreography to Jazz-Funk.
• Katarina's dance references the last dance scene in the movie Napoleon Dynamite.
• Fiddlesticks' dance is a referenced to the Scarecrow Dance in the movie Wizard of Oz.
• Olaf's dance is a reference to the German Technoviking.
• Nautilus' dance reference is the Peeparoonie Dance.
• Kog'Maw's dance is a tribute to Michigan J. Frog from the classic Warner Bros. short One Froggy Evening.
• When Thresh dances, he swings his scythe and his lantern like a pair poi (or kiwido or bolas). The tricks Thresh does is a basic forward weave, a stationary forward windmill and an alternating behind-the-back butterfly.
• Ashe's dance references Alizee's J'en Ai Marre! dance.
• Muay Thai Lee Sin's dance is a reference to Tony Jaa's Training seesion from Ong Bak.
• Twisted Fate's dance is a reference to the extremely popular song Gangnam Style by the korean superstar PSY.
• Syndra's dance is based on the choreography for the song Hoot by Girls' Generation a popular Korean girl group.
• Elise's dance is based off of the Can-Can.
• Vi's dance is a referenc to the Dougie.
• Blood Lord Vlamimir's dance is based off of Contact Juggling.
• Udyr's dance shows the Drunken Master Kung Fu technique.