That's a big question, Tim. You would be best off emailing
fanlegal@oddworld.com and giving them a detailing on what your movie is. I would say that producing it would be no more different than creating fanart or fanfics, but distributing it would be a whole lot different.
I have already, unfortunately, had to decline somebody's request that I host a music video they had made that used footage made by OWI (I did try, but Brinkster wouldn't let me do it anyway). I have another friend who made a trailer for an Oddworld film, and while I haven't seen it, I am assured that it is good. Another bunch of people who haven't seen it are OWI - they are legally unable to watch it.
I fear your project is going to be at the mercy of all kinds of copyrights and trademarks. Email
fanlegal@oddworld.com.