The artwork piece with Crash and Coco in the motorcycle is a parody of the Terminator 2: Judgment Day (1991) movie poster.
First appearance of N. Tropy.
When you defeat Cortex the first time, you'll unlock a secret warp room. The lift to the room is in the center of the main warp room. When you go up the secret warp room, you'll notice an assembly line with Cortex's henchmen in cyborg form with fake skin being laid on them and being sent to different periods of time. This is a reference to the terminators in the Terminator series.
First appearance of Uka Uka, Aku Aku's evil twin brother and Cortex's boss.
The character Dr. Nefarious Tropy (aka Dr. N. Tropy)'s name is a play on the word "entropy" which is the second law of thermodynamics.