A various times in the World Race, car details will appear and disappear based on the needs of the story. For instance, the Nitrox2 tanks on the bottom of Markie's car are clearly visible when he jumps through the spinning wheel (''The Greatest Challenge''). Later, when his car hits the mine and flips, you can no longer see the tanks (or the jump jets).

Thanks to Michael for pointing this out.

Stingray with Nitrox bottles

Stingray without Nitrox bottles

World Race (Full Length Movie) World Race Video Info
Nitrox2 General Info Misc Info
Mark Wylde World Race Wave Rippers Character Info
Greatest Challenge, The (World Race Episode 2) World Race Video Info