All the karts have dual exhaust ports, yet there is only a single smoke stream coming out out of the back of them, and not even out of the ports.
Luigi's portrait shortly after finishing each race is simply a mirrored version of the default portrait, meaning that the L on the cap is backwards.
In Western versions, the "64" sign on Luigi Raceway is re-colored from blue on an orange background to white on a blue background. However, the preview image of this course still uses the color scheme of the "64" sign from the Japanese version.
In the Japanese version, voice actor Charlet Martinet's name in the ending credit is misspelled as "Charles Martinee". This is likely due to a translation error in romanization of Japanese syllables, and due to the fact that the second T at the end of his name is silent.
When Lakitu fishes out racers and returns them each to the course, he is invisible if fishing out AI-controlled racers or when the player's screen shows other racers other than whom the player is controlling being fished out and brought back onto the course.
When Toad is controlled by the player, his scream when falling into hazards or getting hit by objects that send him flying into the air or flatten him is the same when he's spinning out. However, if he's controlled by the AI under these instances, he makes the same scream as if he's rolling down a steep hill.