Before the developers settled on the game's unique painted style, they intended the game to look realistic.

There's an IGN watermark on the covers of both the Wii version and the official strategy guide.

When Mrs. Orange makes the cherry cakes that she promises you, she does a similar move to the Raging Demon that Akuma does in Street Fighter.

During the cutscene before the first battle against Waka, he says "Let's Rock, Baby!" This is a reference to Dante's signature phrase in Devil May Cry. Both games were created by Hideki Kamiya.
In the French verison of the game, Waka's speech translates by "Let's Rock, Baby! As a famous devil hunter will say some day!"
Waka's laser-flute's name is also named "Pillow Talk", the name of the ranking theme in Devil May Cry.

The first time you buy a technique from the Dojo, Onigiri Sensei will "transform" in a similar fashion to that of Viewtiful Joe.

During the fight against Yamata no Orochi, the player can end the first phase of the fight in one blow by simply using an Exorcism Slip L on him while he is vulnerable. This trick only applies to the first Orochi fight; trying to perform the trick in the same way while battling Yamata no Orochi 100 years into the past will still leave him with a third of his health.

When fighting the Kusa 5 in the Wii version, their introductory painting will be of the Earth Mirror; this error is not present in the PS2 and PS3 versions.

After the Moon Cave in Sei'an City is a girl that's drawing. The drawing will be of whatever you had for a mask. She will also ask you to draw a few designs that she thinks will "be the next big hit." The second design she gives you is a V. When you come back to her, she describes it as the "henshin" pattern, which she finds "viewtiful" and exclaims "Henshin-a-go-go, Baby!". This is a clear nod to the Viewtiful Joe series. The third pattern she gives you is the clover pattern, which is a self reference to Clover Studios, the company who made the game. The last design she gives you is the kanji for heaven, which is also used by Akuma from Street Fighter on his Gi.

When learning Cherry Bomb from Tama, he will show a fireworks display called "The Midnight Wonderboy", a reference to Alastor from Viewtiful Joe, as his chapter in that game is called "The Midnight Thunderboy."

Okami's official soundtrack is 5 1/2 hours long. It has 215 tracks on 5 CD's.

The Clovers in the game are references to Clover Studio, the games developer, and when collected play a similar sound to their opening title.

Since Clover Studio is now defunct, this may explained why the Clovers don't appear in Ōkamiden, but instead were replaced with Dandelions.

The name Okami actually has a dual meaning. When written as 狼 or オオカミ, it means "wolf". When written as 大神 (this writing is used in the game's logo), it means "great deity".

This is in reference to the protagonist Amaterasu, who is the Goddess of the Sun reincarnated as a wolf.

Once Orochi is defeated on the PlayStation 2 version, a crescent moon comes out in Shinshu Field. However, a full moon comes out in the Japanese version due to a programming mistake.

In an interview, Hideki Kamiya admitted that early in the development, the team wanted to use the power slash move on the torii gates. However, the team removed the idea, as they all thought to themselves “should a goddess really be doing that?”

An unused enemy named "Gotouryu", a Flying Demon based on the Japanese yōkai of the same name, can be found in the data for the Wii version. When asked about why the enemy was cut, director Hideki Kamiya admitted that he forgot to add the enemy in the game.