The live-action scenes were shot at 23.976fps and telecined: they can be inverse telecined. The effects shots were created at 29.97fps and can’t be inverse telecined: they can be decimated, but that leaves you with jerky movement. One can go ahead and deinterlace them, but the result will be a mess because they’re not really interlaced in the first place. (There might be some hybrid material, but going from memory and a quick look at the first disc, there doesn’t seem to be much.)

Of course, I was assuming NTSC. The effects shots in the PAL versions are more of a mess and do exhibit combing and, I think, some field-blending.