Justin Bailey said:
Do we know that for a fact? Isn't it possible that Rare owns some parts of it (engine or whatever) per some agreement they had with Nintendo?
Nope, Nintendo was the one who aquired the license. Any game Rare made that was a Nintendo license (Donkey Kong, Star Fox, Disney & 007) they gave up any rights to while they aquired sole rights to any co-developed properties.
edit~ lists of who retained what in the Nintendo/Rare split...
Nintendo
-Diddy Kong Racing (N64)
-Donkey Kong 64 (N64)
-Donkey Kong Country (SNES/GBC)
-Donkey Kong Country 2 (SNES)
-Donkey Kong Country 3 (SNES)
-Donkey Kong Land (GB)
-Donkey Kong Land 2 (GB)
-Donkey Kong Land 3 (GB)
-Goldeneye 007 (N64)
-Ken Griffey Jr.'s Winning Run (SNES)
-Mickey's Racing Adventure (GBC)
-Mickey's Speedway USA (N64/GBC)
-Star Fox Adventures (GC)
Rare
-Anticipation (NES)
-Banjo-Kazooie (N64)
-Banjo-Tooie (N64)
-Blast Corps (N64)
-Captain Skyhawk (NES)
-Cobra Triangle (NES)
-Conker's Bad Fur Day (N64)
-Conker's Pocket Tales (GBC)
-Jet Force Gemini (N64)
-Killer Instinct (AC/SNES/GB)
-Killer Instinct 2 (AC)
-Killer Instinct Gold (N64)
-Perfect Dark (N64/GBC)
-Pin Bot (NES)
-R.C. Pro-Am (NES)
-Slalom (NES)
-Snake Rattle 'N' Roll (NES)
-Solar Jetman (NES)
-Super R.C. Pro-Am (GB)