I'm not quite sure if "title sequence" is the phrase I'm looking for, so I'll explain what I mean.
Older movies would begin with a short credit sequence, which would also include the title of the movie. Recently, it is becoming more common to skip this in preference of showing the title at the end of the movie, perhaps as part of the credits.
What I'm wondering, is if there has been an instance of a movie being produced without any inclusion of its title in such a sequence. If there is some legal requirement to have the title listed somewhere (e.g. copyright notice) then those mentions can be ignored. If there has been a movie produced with no title at all then I suppose it would qualify by default.