It could be something visual, a sound effect, or even a funny character or place name (such as "Dr. Puzz" sounding like "Octopus" when you say it fast) - whatever you'd like to share.
Here are some visual ones I have to share with screenshots.
The King on the card showing out of the top of the card deck enemies is Capital B!

The hieroglyphs around the walls of Capital Cashino repeatedly spell "PLAYTONYC [sic] GAMES YOOKA LAYLEE" (someone in the team needs to go back to Gobi's Valley to brush up on their hieroglyphics!

The carpet pattern contains the conical flask and triangle shapes from the Playtonic Games logo.
Amusing book title "How to use hexagons in all your home decorating!". Capital B certainly read that book thoroughly when designing his lair!
Amusing book title "50 Shaders of Games".

The "Slippy Edition" of the book "The Slide From The Top" because the book is angled to form a slide.
A matching "Step Edition" called "To The Top! How I Stepped Up!" when the books form stairs.
The special "Domino Edition".

Poor discarded "Vice-Prezedent" Dr. Quack statue abandoned in a lonely corner of the Hivory Towers Lair.
Love the "Pants and why you should wear them" brochure taking a light-hearted stab at the people who complained that Yooka needed pants when the title characters were first revealed.
Some helpful tips on the back of the multi-coloured paint tin, such as "Do not paint your cat" and "Do not apply to butt".

Please post anything amusing you have noticed, as I'd love to see what other fans have found!