Franchise: Kirby

The Kirby series has used a crescent moon as a door to a secret area filled with items on multiple occasions:

• In Kirby's Dream Land, the moon can be entered on Stage 4, Bubbly Clouds.
• In Kirby's Adventure, the same moon can be entered on Stage 6 of Rainbow Resort, which is a stage designed as an abridged remake of the first game.
• In Kirby Super Star, the moon can be entered in the Bubbly Clouds level of Spring Breeze, a sub-game that also acts as an abridged remake of the first game.
• In Kirby Triple Deluxe, the moon in Stage 6-1 leads to a HAL Room.
• In Kirby: Planet Robobot, the holographic moon on Stage 6-8 leads to a rare sticker.

In 1996, the Club Nintendo magazine in Germany printed a comic titled Kirby's Biggest Case, depicting the usually lovable Kirby as a depraved detective who smokes, drinks alcohol, reads "dirty magazines", and sneaks into women's restrooms. Writer Claude M. Moyse claimed that this portrayal of the character as, in his own words, "a freak" was a way of getting back at creator Masahiro Sakurai, who he had a grudge against for unknown reasons.

Series director Shinya Kumazaki maintains an art gallery on his personal website where he showcases paintings that he makes in his spare time. Several of these pieces depict dystopian surrealist versions of characters from the Kirby franchise, including Miracle Matter, Queen Sectonia, Taranza, and Drawcia.

In an interview with Polygon writer Chris Plante, series director Shinya Kumazaki stated that although Kirby appears to devour his enemies, the foes that he swallows are not killed; instead, they simply get "poofed" elsewhere in the world. According to Kumazaki, this concept is meant to make the series more approachable to lay audiences by presenting a comedic alternative to the "extreme or violent expression" of Kirby digesting his opponents.

According to Masahiro Sakurai in a YouTube video he made on Kirby's Dream Land, the character's signature float came about as a way to avoid losing a life when simply missing a jump in a heavy platforming section, as he found such an occurrence in games like Ninja Gaiden and Castlevania, among others, to be particularly frustrating.

According to Masahiro Sakurai on his YouTube channel, he thought a lot about how to implement the unique gameplay element of Kirby using each of his enemies as an attack, which originated from Sakurai's need for a "Risk-Reward" system for his game. He even revealed that an early concept of this was Kirby using a long tongue, instead of his signature vacuum, to catch and consume enemies, and he further stated that this concept predated Yoshi's tongue attack too.

In an interview with Satoru Iwata and Masahiro Sakurai for the Japanese exclusive game guide for Kirby's Adventure, Sakurai stated that they wanted a character that a person could draw in a sketchbook easily, which resulted in the main character Kirby.

The way Wheel Kirby uses his Rocket Start move in Kirby Triple Deluxe and Kirby: Planet Robobot bares a striking similarity to the Spin Dash move used by the titular character of the Sonic The Hedgehog franchise.

After the anime series Kirby: Right Back at Ya! came to the West, the logos for almost every Kirby game since then have been stylized the same way, starting with Kirby: Nightmare in Dream Land.

Archie Comics attempted to obtain a licence from Nintendo to make Kirby comics, but failed to do so.

Although Meta Knight first appeared in Kirby's Adventure, he wasn't given a name until the release of Kirby's Avalanche.

Sword Kirby bears a strong resemblance to Link from The Legend of Zelda series, and like Link, can shoot sword beams at full health. Despite minor differences in the hat and sword designs, this is clearly an intentional reference, both Kirby and Link being well known Nintendo characters.

The enemy Pacto bares a resemblance to Namco's mascot, Pac-Man, as both have the same yellow skin color and they both open and close their mouths in similar fashions.

A program titled "Kirby Family" (a spiritual successor of Mario Family) was planned to be released for the Game Boy Color. The game was showcased at Spaceworld 2001, but the plans to retail it outside of the event for 6,800 yen on September 10, 2001 were scrapped.

In the Japanese version of several Kirby games released since 2011, during the tutorial, a red circle will appear whenever an action is properly done. However in the international version, the red circle was replaced with a green check mark, possibly to not confuse the player whenever they performed a correct action. In Japan, a circle is used in the same manner as a tick is in the west.

The recurring enemy Cappy resembles a modern interpretation of a Haniwa doll if his mushroom "cap" is removed.

When Meta Knight is defeated in Kirby's Adventure, his mask breaks revealing his face to be identical to Kirby's, hinting that Kirby and Meta Knight are the same species.

Whip Kirby is a possible reference to Indiana Jones, as Jones has an extensible coiled whip that can be used to grab objects. Kirby also has Jones' hat, only with a star motif.

For the "Kirby: Right Back at Ya!" 3D episode on the Nintendo 3DS, most of original cast members were brought back to reprise their roles. The only exceptions were Maddie Blaustein, who didn't return to voice Chef Kawasaki as she passed away in 2008, and Andrew Rannels, who didn't return to voice Nightmare as he had a busy career on Broadway.

While most abilities got hats in Kirby Super Star, the Hammer ability didn't get one. The current hat seen today first appeared in the Kirby anime, with some minor tweaks.