It isn't like that, and what I wrote above is likely wrong.
The game uses a unique microcode. The N64 has a programmable video processor, so all video display is done in a sort of shorthand (microcode) that is processed very quickly with no error detection. This is then interpretted and a snopshot of the screen is output as a result.
Nintendo provided several video processing formats, each with its own unique microcode. These games, like many racing games, use a nonstandard format designed by the company, seemingly much lower level and with a special selection scheme to cull anything that isn't immediately on screen.
There's at least somebody working on this right now, and the debugger has been reactivated in WDC. It may take some time, but eventually the format will be reverse-engineered.