PAL is the TV standard used in most of Europe, while NTSC is used in the US and Japan. PAL runs at 50 frames per second, while NTSC runs at 60. Therefore, conversions from original NTSC games to PAL either have to be sped up to compensate for the lower frame rate, or (more often) just left running 12% slower than the NTSC version.

The N64 didn't suffer from PAL slowdown as much as the old SNES and Genesis though - perhaps the games were optimised?

Oh, and regarding the MM ending - I have the Collectors Edition on Gamecube and an emulated version. The Collector's Edition version runs at 60 fps, but the emulated version I have is PAL and runs at 50 fps.
The ending I've noticed has a slight difference. At one point in the PAL version, under the credits you see a spinning Bunny Hood mask. On the NTSC version, this is a shot of the couple outside the Bomb Shop.