I found some lost footage of a beta build of Crash Nitro Kart on a French website. One of the videos is a battle against Krunk, which contains a lot of differences. Here are some of the differences I could notice:

• Cortex and Krunk spawn much further ahead of the finish line.
• The powerslide bar has the colors reversed.
• Some debug coordinates appear below the time.
• The HUD doesn’t display the player’s position number.
• The lap counter doesn’t have the “LAP” text.
• Krunk doesn’t have animations.
• The boss kart has a black color and a different engine sound.
• There’s no X Crates in the boss race.
• Some power-ups have different icons.
• The item roulette gives an item too early.
• Krunk’s hazards are very different.
• Krunk doesn’t have voice clips.
• The minimap is larger and higher on the HUD.
• There’s a height meter that would pop up every time the kart was lifted from the ground.
• Krunk’s icon on minimap is black.
• The boost counter appears on the right and over the minimap.
• The CNK ribbon have a totally different texture.
• Jungle Boogie uses Tiny Temple’s theme.

Original source: Gamekult