X-Rated Eyes...
A neat little detail that I just happened to catch during a video replay... Whenever Koopa Paratroopa spins out, his pupils turn into little 'Xs' for a few seconds. Such a tiny small little observation that I'm not at all surprised that it took me this long to notice.

Wide Load...
Ask Wario to use an item when he doesn't have one, and he makes a gesture with his hands. Although it could be interpreted as anything, I swear he's fanning and shaking his ass to taunt anyone behind him. I suppose the meaning of this motion could be open to interpretation.

High Dive...
After the staring line on Yoshi Circuit and after a few turns, there's a hidden pool high up on a hill. I was fooling around with the jump code for Action Replay when I first found it.

Stupid Shortcut...
The big square 'windows' on the tunnel of Yoshi Circuit have always caught my attention... I decided to try the jump code, and see if I could fly across the water in midair, and take a bit of a shortcut by hopping through one of these openings... No such luck. There's an invisible barrier here, so my Kart fell in the ocean.

Hang a Left...
After the tunnel in Yoshi Circuit, is a sign that says 'Turn Left'. It seems like a pretty basic instruction, but it's strange that I never noticed this before. I used the jump code to snap this screenshot, which is the only way to get a really decent look at it. Very strange.

Star Scraper...
This unique tower in Mushroom City has always caught my attention. It's covered with star lights (or are those windows?). At first, I thought it was inspired by Bowser's shell, thinking that the corners of the top were spikes... But by taking a break from racing and actually inspecting the design, it seems like a giant octagon instead of spikes.

Super Signs...
On the tops of buildings in Mushroom City, we can see a couple billboards with references to classic Mario... The one on the left is "Super Star", with the 'A' being an actual star. On the right, is a 'Super Mushroom' sign on top of a store... I think I can even see stars on either side of 'Super'.

High on Shrooms...
Something that was spotted in Mushroom City, were the tops of a few buildings that very closely resemble Mushrooms... Was this something that was designed by the architects who built the city, or is it real fungus...?

Birdo Billboard...
A sign for Birdo Ribbon was found near the end of Yoshi Circuit, and I've also spotted a similar graphic on a building in Mushroom City.

Banner Blast...
Each of racetrack in Double Dash has its' own unique banner at the starting line. In Mushroom City, the banner has "Donkey Kong" style lettering. I noticed the style before, but it just hit me that the font appears to be inspired by DK.

Building Banners...
Again in Mushroom City, there's a large building not to far off the staring line. The doorway has stars above it, with another 'Mario Kart' banner higher up on the building. The same building also has a vertical 'Mario Kart' banner running vertically on the side of the building.

Snow Star...
A group of stars similar to this one were featured on a previous 'Stuff update on Mario Circuit... Another set stars have been found on Sherbet Land, with a blue 'Mario Kart' with a crown graphic and the GameCube logo.

Frozen Fortresses...
Sherbet Land also has some blue stone castle structures off in the distance. From this high vantage point, we can get a look at these fortresses as they stick out of the frozen background.

Star Box...
Stars are being frequently spotted as background details on the racetracks, and I just noticed this one on Peach Beach... To the left of the starting line, is a giant crate with a star on it.

Confusing Code...
Stone carvings have been found in the cave of Dino Jungle, resembling a Stegosaur and a Pterodactyl... But as you leave the cave, you head over a small ramp. The back of the ramp is covered with carvings that you wouldn't normally see. (This screenshot was taken while driving backwards). I couldn't find a clear meaning for these symbols, and they appear to be random...