subdirectory_arrow_right Wario World (Game), Wario (Franchise), Nintendo (Company)
Attachment was an official Nintendo website made as a hub for developers and publishers licensed to work on Nintendo hardware. The site used Wario as a mascot, something that may not seem strange as his profession is designing video games in the WarioWare series. However, the site was opened in 1997, predating WarioWare by multiple years, and also predates the Wario World game for GameCube. Instead of renaming the site to avoid confusion and using the URL for the game's US promotional site, the URL was used for the game's website, something that more than likely caused confusion for Wario fans. WarioWorld was closed in 2016, having recieved very few visual updates since the 1990s, and now redirects to a more modern and professionally designed Nintendo developer hub.
person Rocko & Heffer calendar_month December 18, 2023
Archive of a Supper Mario Broth post about WarioWorld:

Forum thread about Wario World's promotional website, showing a screenshot with the URL:
subdirectory_arrow_right WarioWare: Move It! (Game), Wario (Franchise), Wario Land (Collection)
In the cutscenes for Kat & Ana's stage in WarioWare: Move It!, Cractus from Wario Land 4 appears. This is the first time a Wario Land character has appeared in the cutscenes of a WarioWare game.

In the Japanese version of Move It!, Cractus has a slightly different name from the Cractus that appeared in Wario Land 4.

The latter game's Cractus was called フラワナ, or Furawana, a pun on "flower" and「罠」(wana, trap). The former that appears in Move It! however is called フラワニ, or Furawani, a pun on "flower" and「鰐」(wani, crocodile). This name change could mean the character was renamed, or the Cractus in Move It! is meant to represent a different individual from the same species.
person Rocko & Heffer calendar_month November 17, 2023
Cractus in Move It:

Move It's English character scroll, confirming that Cractus is in the game:

Move It's Japanese character scroll:

Wario Land 4 Japanese version Cractus boss fight:
subdirectory_arrow_right WarioWare: Touched! (Game)
Nintendo Treehouse did not expect the WarioWare series to receive more installments after WarioWare: Touched!. They also did not believe that the character Ashley would not make any further appearances in the Wario franchise as a whole, so they cast a random localization employee named Christine Peyser to play Ashley in the English version of the game instead of a professional voice actress. This would become problematic as the WarioWare series proved its longevity, with Peyser being forced to abandon projects to record Ashley's lines. Ashley, alongside the entire WarioWare cast sans Wario, would eventually be recast in WarioWare Gold.
person Rocko & Heffer calendar_month September 26, 2023
Part-Time Gamers - Episode 76 (from 46:30):

WarioWare Inc., Mega MicroGame$! end credits:
Attachment Pyoro, the star of the game-within-a-game series that rivals Wario's microgames in the WarioWare series, is a parody of the Japanese malt chocolate ball brand Chocoball's mascot, Kyoro-Chan.